Contributor disclosures are reviewed for conflicts of interest by the editorial group. When found, these are addressed by vetting through a multi-level review process, and through requirements for references to be provided to support the content. Appropriately referenced content is required of all authors and must conform to UpToDate standards of evidence.
INTRODUCTION — The treatment of psoriatic arthritis (PsA) involves the use of a variety of interventions, including many of the agents used for the treatment of patients with other forms of inflammatory arthritis, particularly spondyloarthritis and rheumatoid arthritis (RA), and others employed for the management of the cutaneous manifestations of psoriasis.
Although a number of medications are effective in the treatment of both RA and PsA, trials involving some classes of biologic agents indicate that patients with RA and PsA can also experience markedly different responses to some drug classes. Treatment of the different elements of psoriatic arthritis includes coordinated intervention to address the major domains of the disease, including peripheral and axial arthritis, enthesitis, dactylitis, and skin and nail involvement. (See "Clinical manifestations and diagnosis of psoriatic arthritis".)
The treatment of PsA, including peripheral and axial arthritis, enthesitis, and dactylitis, is discussed in this topic review. The treatment of psoriatic skin and nail involvement, the clinical manifestations and diagnosis of PsA, and the pathogenesis of PsA are presented separately. (See "Treatment of psoriasis" and "Nail psoriasis" and "Clinical manifestations and diagnosis of psoriatic arthritis" and "Pathogenesis of psoriatic arthritis".)
MANAGEMENT PRINCIPLES AND PRETREATMENT INTERVENTIONS — The approach to treatment includes therapy for both musculoskeletal disease, including peripheral and axial arthritis, enthesitis, and dactylitis, and disease of the skin and nails, and is aimed at controlling inflammation and preventing discomfort and damage [1,2]. More than one type of musculoskeletal involvement, and frequently cutaneous involvement, often occur in individual patients. General principles of treatment for psoriatic arthritis (PsA) include:
●Patients benefit from evaluation and treatment early in the disease by clinicians with expertise in the care of patients with rheumatologic conditions [3,4] (see 'Prognosis' below), and treatment should be coordinated between the rheumatologist, primary care clinician, and other specialists (eg, the dermatologist). Differences in response between the skin and joints, and the different musculoskeletal manifestations to individual therapies, are commonly observed.
●Treatment is guided initially by an assessment of disease severity, including the degree of disease activity, damage, and impact on the patient for each clinical domain, followed by initial attention to the most severely involved region such as axial or peripheral arthritis. Due to the common involvement of multiple domains (peripheral arthritis, axial inflammation, dactylitis, enthesitis, skin, and nails) in a single patient, additional considerations regarding optimal therapy may be required. Initiation of a biologic agent for the management of one clinical manifestation (eg, axial arthritis or moderate to severe skin disease) may eliminate the need for additional therapies in the treatment of another manifestation (eg, trial[s] of a conventional disease-modifying antirheumatic drug [DMARD] for peripheral arthritis before use of a biologic agent).
●A treat-to–target approach should be employed for peripheral and axial arthritis, with a target of remission or minimal disease activity . Evidence suggests that this type of approach can result in improved patient outcomes and reduced disease progression, as progression of damage is predicted by persistent joint inflammation [6-9].
●Comorbidities (eg, diabetes, metabolic syndrome, fatty liver, coronary artery disease) are prevalent in PsA and should be identified because they can affect overall health and treatment selection. Patients should be referred as needed for prevention and medical management of these comorbidities. This last point is particularly important because many patients may be receiving care from a rheumatologist and dermatologist but not a primary care clinician.
●Pretreatment screening for comorbidities and baseline testing before drug administration in all patients should include screening for cardiovascular risk factors (lipids, blood pressure, and smoking), weight loss counseling for patients with elevated body mass index (BMI), and evaluation (eg, ultrasound) of the liver for patients with elevated liver function tests (LFTs); eg, greater than three times the upper limit of normal . Additional testing should include screening for hepatitis in patients initiating methotrexate (MTX) therapy and screening for latent tuberculosis in patients who may receive biologic agents.
●Patients should undergo vaccinations relevant to treatments that may be planned.
NONPHARMACOLOGIC TREATMENT — The following nonpharmacologic management strategies are important in the treatment of psoriatic arthritis (PsA) in addition to drug therapy:
●Exercise, physical therapy, and occupational therapy – Patients should be referred for physical therapy (PT) and occupational therapy (OT), encouraged to exercise, referred as needed for orthotics, and educated about joint protection.
●Weight reduction – Obesity and metabolic syndrome are common comorbidities in PsA and may lessen treatment response to disease-modifying antirheumatic drugs (DMARDs) and/or biologic agents . Patients should be counseled about proper eating habits and referred to nutritionists for further counseling if appropriate.
•Patients should be educated as to the nature of their condition and to the effect of stress on their disease, as well as the importance of following up for appropriate management of increased cardiovascular risk associated with the disease and other comorbidities. (See "Clinical manifestations and diagnosis of psoriatic arthritis", section on 'Comorbidities' and "Comorbid disease in psoriasis".)
•Patients should also be instructed about their medications and the proper use of topical and oral medications, as well as the need for regular drug administration and monitoring of disease activity and for side effects of therapies.
Overview of approach — The choice of therapy for peripheral arthritis is based upon the severity of disease and the patient’s response to treatment. It may also be influenced by comorbidities, patient goals and preferences regarding routes of drug administration and cost of treatment to the patient, and regulatory and insurance requirements.
●Mild arthritis – Patients with mild peripheral arthritis may be effectively treated by use of a nonsteroidal antiinflammatory drug (NSAID). (See 'Mild arthritis/NSAIDs' below.)
●Moderate to severe arthritis or resistant to NSAIDs – Patients with moderate to severe arthritis or who are resistant to initial NSAID therapy alone are usually treated with a conventional disease-modifying antirheumatic drug (DMARD), such as methotrexate (MTX) or leflunomide (LEF), unless a biologic DMARD is required for the treatment of other disease manifestations (see 'Moderate to severe arthritis or resistant to NSAID' below). Some patients with mild to moderate arthritis benefit from apremilast, which can be used instead of a nonbiologic or biologic DMARD. In particular, it can be useful for patients who wish to avoid DMARD therapy, infusions, or injections, although only a portion of patients respond. (See 'Apremilast' below.)
●Severe disease at presentation – In patients presenting with severe disease, such as those with many involved joints, erosive disease at presentation, and functional limitation, we suggest a biologic DMARD (eg, a tumor necrosis factor [TNF] inhibitor) as first line therapy, rather than a conventional nonbiologic DMARD. We prefer this approach because of its capacity to limit joint damage and more rapidly restore function. (See 'Severe peripheral arthritis/adverse prognosis' below.)
●Resistant to nonbiologic DMARD – In patients with peripheral arthritis but an inadequate response to a conventional DMARD, treatment with a biologic DMARD, such as a TNF inhibitor, is usually indicated. (See 'Resistant to nonbiologic DMARDs' below.)
Since progressive joint damage is more likely in patients with a larger number of inflamed joints at the outset, patients with polyarticular involvement may benefit from early introduction of DMARDs. Notably, however, no DMARDs have been proven to slow or prevent radiographic damage. Thus, the role of these agents for patients with baseline damage is of uncertain value but is often required when access to TNF inhibitors is limited.
The choice of the DMARD depends, in part, upon whether the patient has active or severe psoriasis as well as arthritis. Medications used for control of psoriasis should be considered in individuals in whom the psoriasis and arthritis are of roughly equal severity. Drugs such as MTX, photochemotherapy with psoralen plus ultraviolet A (PUVA), use of retinoic acid derivatives, and cyclosporine A have been shown to improve both the joint and skin manifestations of psoriasis [1,2,12-14]. However, none of these medications has actually been shown to prevent or retard progression of joint damage. Inhibitors of TNF-alpha may also be effective for both skin and joint disease.
Mild arthritis/NSAIDs — In patients with mild arthritis, defined as disease involving less than four joints, no radiological evidence of damage, and minimal discomfort or functional impairment, we suggest initiating treatment with an NSAID (eg, naproxen 375 to 500 mg twice daily, or celecoxib 200 mg twice daily) rather than starting a DMARD [1,2].
Other NSAIDs that we use in patients with peripheral arthritis include ibuprofen (up to 2400 mg/day), diclofenac (up to 150 mg/day), or ketoprofen (up to 200 mg/day) for patients with peripheral arthritis. There is general consensus by experts that NSAIDs, including both nonselective NSAIDs, such as naproxen, and cyclooxygenase (COX)-2 selective NSAIDs, such as celecoxib, can help control the mild inflammatory symptoms of PsA and may also lessen pain and stiffness in spondylitis, although there is very limited evidence from randomized trials in patients with PsA [1,2,15-17]. While there has been some concern that NSAIDs may aggravate the skin psoriasis [12,18], in one randomized trial of a COX-2 selective inhibitor (which was not approved for commercial use) there was no significant difference in an index of skin involvement between the two groups .
Comparative studies have not found any difference in efficacy between different NSAIDs. As a result, the choice of an NSAID depends upon the individual clinician’s familiarity with a particular drug, patient preference regarding frequency of administration, and individual patient tolerance. The COX-2 selective inhibitor etoricoxib can also be given in a once-daily dosis of 60 or 90 mg, but this drug is not available in the United States or Canada.
One difficulty with NSAIDs, particularly in PsA where many patients may already have increased cardiovascular risk, is the additional cardiovascular risk typically associated with the use of these agents. (See "Nonselective NSAIDs: Adverse cardiovascular effects" and "COX-2 selective inhibitors: Adverse cardiovascular effects".)
An alternative agent for use in patients with mild PsA and multiple comorbidities is apremilast, particularly in patients who wish to avoid DMARD therapy, infusions, or injections, although only a portion of patients respond. (See 'Apremilast' below.)
In patients with only one or two swollen joints (mono- or oligoarthritis), we generally perform a joint aspiration and intraarticular glucocorticoid injection. Although there are no randomized trials demonstrating efficacy of intraarticular injections, an observational cohort study revealed effectiveness of intraarticular injections in PsA . Care should be taken in patients who require intraarticular glucocorticoid injections to avoid injection through psoriatic plaques. We generally avoid the use of oral glucocorticoids. (See 'Role of glucocorticoids' below.)
Moderate to severe arthritis or resistant to NSAID
Choice of nonbiologic DMARD and other agents — We take the following approach:
●In patients whose peripheral arthritis remains active (ie, persistent joint inflammation) despite the use of NSAIDs, we suggest starting with a conventional (small molecule) DMARD rather than a biologic agent. We prefer MTX (15 to 25 mg once weekly) in patients with peripheral arthritis who lack axial symptoms or in whom axial symptoms that may be present, such as back pain, are well-controlled with NSAIDs (see 'Methotrexate' below). We also use this approach for initial therapy in patients with more than mild disease who lack erosive joint changes or substantial functional limitations. (See 'Severe peripheral arthritis/adverse prognosis' below.)
●We initiate or continue NSAIDs as bridging or adjunctive therapy as needed in patients begun on DMARDs. (See 'Mild arthritis/NSAIDs' above.)
●In patients who are intolerant of MTX, unwilling to use this agent (eg, because they perceive it as “chemotherapy”), or unresponsive to MTX, we use LEF (20 mg daily) (see 'Leflunomide' below). However, unlike MTX, which is also effective for psoriasis in some patients, LEF is generally not beneficial for the skin disease.
●Other medications may be used occasionally in individuals with PsA unable to use MTX or LEF and in whom the psoriasis does not pose a particular problem. Included in this group are sulfasalazine (SSZ), antimalarials, and azathioprine. We usually use SSZ as an alternative to MTX in patients with a contraindication to MTX or LEF (eg, refusal or inability to give up alcohol intake), but the likely degree of benefit is low. (See 'Sulfasalazine' below.)
●Some patients with arthritis benefit from apremilast, which can be used instead of a nonbiologic or biologic DMARD. It may be useful for patients who wish to avoid DMARD therapy, infusions, or injections, although only a portion of patients respond. It should not be used in patients with erosive disease, as the capacity of apremilast to prevent joint injury has not been established. (See 'Apremilast' below.)
MTX use and efficacy — MTX should be increased rapidly as tolerated to 15 mg orally once weekly then as required up to the 25 mg once weekly. Patients receiving MTX should also be treated with folic acid (1 mg daily) to reduce the risk of adverse effects. (See "Use of methotrexate in the treatment of rheumatoid arthritis".)
Prior to initiating MTX therapy, patients should undergo routine laboratory testing, including hematology and biochemistry to confirm normal liver function. They should also have their hepatitis status tested, as well as a chest radiograph. Any required vaccinations should be administered before initiating DMARD therapy. The use of MTX in patients with obesity and/or type II diabetes mellitus should be avoided, if possible, given the increased risk of hepatic fibrosis in patients with these comorbidities . (See 'MTX safety and monitoring' below.)
In patients with an inadequate response to doses of MTX greater than 17.5 mg weekly given orally, we switch to the subcutaneous route, which improves absorption of the medication, as shown in rheumatoid arthritis (RA), and which patients may self-administer. Alternatively, splitting the dose over a 24-hour period orally (morning, evening, and next morning) may improve pharmacokinetics and pharmacodynamics (see "Use of methotrexate in the treatment of rheumatoid arthritis", section on 'Dosing of MTX'). With the correct dose, a response should occur within eight weeks of initiating therapy.
In patients using parenteral rather than oral MTX, the subcutaneous route may be more beneficial than the intramuscular route and is more convenient for patients who can self-administer the medication. Parenteral MTX can be increased up to 25 or, rarely, 30 mg/week.
Folic acid supplementation should be provided to all patients taking MTX. Dose frequency ranges from daily to once a week. Patients who do not have a satisfactory response to folic acid or poorly tolerate it may instead be prescribed folinic acid, usually the day after MTX. (See "Major side effects of low-dose methotrexate", section on 'Prevention of side effects with folate' and "Use of methotrexate in the treatment of rheumatoid arthritis", section on 'Folic acid supplementation'.)
MTX is the most commonly used first-line DMARD in PsA, although only limited data are available supporting its efficacy in PsA. Despite the lack of randomized trial evidence of efficacy, observational studies and our clinical experience indicate that MTX may be effective for some patients in clinical practice [21-23]. Expert opinion also supports use of MTX as a first-line DMARD, including treatment guidelines of the European League Against Rheumatism (EULAR) [16,24] and the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) [17,25]; we prefer it as well based upon ease of use, tolerability, and proven efficacy in psoriasis. (See "Treatment of psoriasis", section on 'Methotrexate'.)
While most randomized trials and other studies using MTX have not shown significant benefit, they have all had significant limitations, including the use of lower (sometimes much lower) doses of MTX than are routinely used in practice; patient populations with very longstanding disease, often more than 10 years’ duration; small numbers of subjects; trials of short duration; and other elements of poor study design. For example, the largest randomized controlled trial with MTX was the Methotrexate in Psoriatic Arthritis (MIPA) trial, which failed to show that MTX was superior to placebo . Although this trial did not show efficacy of MTX over placebo, the maximum dose was only 15 mg weekly given orally, the burden of joint involvement was low, and the high dropout rate may have reduced the strength of the trial. The Etanercept and Methotrexate in Combination or as Monotherapy in Psoriatic Arthritis trial (also termed the SEAM trial; ClinicalTrials.gov identifier: NCT02376790) is a randomized trial that is ongoing and will provide additional evidence to inform treatment choices. Prevention of radiologic joint injury has not been demonstrated.
The maximal response to MTX is usually achieved within three months of treatment with the drug. Patients who do not respond to MTX 25 mg/week for six to eight weeks are unlikely to respond to more prolonged therapy. On the other hand, discontinuation of MTX in responders is often associated with severe flares of both skin and joint disease. We thus suggest that patients who wish to discontinue MTX do so using a slow taper. (See "Use of methotrexate in the treatment of rheumatoid arthritis".)
MTX safety and monitoring — The most serious potential side effects of MTX include liver toxicity, interstitial lung disease, and bone marrow suppression. Data are not available for prevalence of liver toxicity in PsA. However, in a study of 71 psoriasis patients on MTX, 169 serial biopsies were analyzed, and type 2 diabetes and obesity were major risk factors for progressive fibrosis even at lower doses of MTX . The role of liver biopsy in monitoring hepatotoxicity in patients treated with MTX has been controversial. One study of 54 patients with psoriasis or PsA treated with MTX for a mean of 6.9 years found that the use of laboratory tests alone could adequately identify liver toxicity .
National organizations have published different recommendations concerning the role of liver biopsies:
●The American Academy of Dermatology (AAD) and the National Psoriasis Foundation do NOT require liver biopsies in all patients administered MTX [27,28]. There are no specific guidelines for patients with PsA [29,30]. (See "Treatment of psoriasis", section on 'Hepatotoxicity and liver biopsy'.)
●The American College of Rheumatology (ACR) has recommended pretreatment liver biopsies only for patients with a significant history of alcohol consumption, with persistently elevated liver enzymes, or with a history of chronic hepatitis B or C infection; and repeat biopsies as indicated by liver test abnormalities . The latter guidelines were originally developed specifically for patients with RA, who may have different liver sensitivity to MTX than patients with PsA.
We generally follow the guidelines of the ACR with regard to pretreatment biopsies, but we tend to perform repeat biopsies more commonly in patients with PsA than in those with RA. (See "Hepatotoxicity associated with chronic low-dose methotrexate for nonmalignant disease", section on 'Guidelines in other rheumatic diseases'.)
Caution is necessary in patients with impaired renal function. Patients with severely reduced glomerular filtration rates (GFR; eg, GFR <20 mL/min, serum creatinine >3.4 mg/dL [300 micromol/L]) should not receive MTX; those with less marked impairment may cautiously take the drug at a reduced dose with close monitoring. (See "Chemotherapy-related nephrotoxicity and dose modification in patients with renal insufficiency", section on 'Methotrexate'.)
Leflunomide — We use LEF (20 mg daily, taken orally) in patients who have persistent joint inflammation despite three months of treatment with MTX (in maximal doses up to 25 mg weekly subcutaneously) and in patients who are unable to tolerate MTX due to adverse effects, such as liver toxicity. LEF can also be prescribed as a first-line DMARD for patients with a low skin burden of psoriasis. In addition, the use of LEF following an inadequate response to MTX may be required by some insurers or regulatory agencies prior to the approval of a biologic DMARD. The dosing, adverse effects, and monitoring of LEF are the same as in patients with RA and are discussed in detail separately. We do not use a loading dose, as reported in some studies , because of the higher rate of gastrointestinal side effects with this approach. (See "Leflunomide in the treatment of rheumatoid arthritis" and 'Monitoring' below.)
The benefits of LEF in patients with PsA have been shown in a small number of randomized trials and observational studies [32-36]. In our experience, LEF is effective in about 40 percent of patients. It also improves skin disease, but may be less effective for the skin changes than MTX . Treatment for a total of three months is usually adequate to determine the maximal degree of benefit. Effects on progression of radiologic joint damage have not been demonstrated.
In one representative randomized trial involving 190 patients with PsA, in which the efficacy of LEF was compared with placebo, a significantly higher proportion of LEF-treated (100 mg/day loading dose for three days followed by 20 mg daily), patients were classified as responders at 24 weeks, based upon scores on the PsA Response Criteria (PsARC), an index of PsA activity (59 versus 30 percent) . LEF was also effective in controlling skin disease, as measured by greater improvement in Psoriasis Area and Severity Index (PASI) scores (22 versus 2 percent). Diarrhea and increased serum aminotransferase levels were more frequent in the group receiving LEF, as has been observed in RA (see "Leflunomide in the treatment of rheumatoid arthritis"). Effects on progression of joint damage were not assessed in this trial.
Apremilast — In patients with PsA and nonerosive inflammatory arthritis, particularly those with multiple comorbidities, we suggest apremilast (30 mg twice daily following an up-titration at a rate of 10 mg daily over six days), a novel, orally administered phosphodiesterase-4 inhibitor. Apremilast may also be of benefit in patients with enthesitis and dactylitis early in disease course (see 'Enthesitis and dactylitis' below). It may be particularly appropriate for PsA patients with multiple comorbidities, given the excellent safety profile and documented efficacy in randomized trials for both psoriasis and PsA. It is also useful for patients who wish to avoid DMARD therapy, infusions, or injections, although only a portion of patients respond. Some patients require up to four months of treatment to achieve a maximal response to the drug.
Apremilast should not be used in patients with erosive disease, as the capacity of apremilast to prevent joint injury has not been established or adequately examined in PsA or in other forms of inflammatory arthritis.Routine laboratory monitoring is not required, but baseline serum creatinine is important because the dose should be reduced to 30 mg once daily in patients with creatinine clearance estimated at less than 30 mL/min. The role of apremilast in PsA remains to be determined as greater experience is gained with this agent. We generally do not combine it with biologic agents because of the lack of information on benefit and risk with these combinations.
Apremilast is available for the treatment of PsA in the United States, Canada, and Europe ; it is under review in other regions as well. The drug modifies multiple proinflammatory mediators and cytokines involved in the innate and adaptive immunity [38-40]. It is not known whether it has disease-modifying properties, such as the ability to prevent or reduce joint damage. Apremilast is also available for the treatment of psoriasis and the beneficial impact on skin disease is similar to MTX, but the drugs have not been directly compared. It has gained favor with dermatologists based upon the low toxicity profile. (See "Treatment of psoriasis", section on 'Apremilast'.)
The efficacy and safety of apremilast for the treatment of PsA has been shown in several randomized trials in which ACR composite criteria for at least 20 percent improvement, termed an ACR20 response, was achieved in patients receiving 30 mg twice daily after 16 weeks in about 40 percent of patients [40-42]. As an example, in a phase 3 randomized trial involving 504 patients with active PsA, the Psoriatic Arthritis Long-term Assessment of Clinical Efficacy (PALACE-1) trial, apremilast (20 or 30 mg twice daily) was significantly more likely than placebo to result in an ACR20 (31 and 40 versus 19 percent) at week 16 . Benefit was observed in patients on both background traditional DMARDs (eg, MTX, LEF, and/or SSZ) and in patients not on DMARDs. A minority of the patients had previously received a biologic DMARD; some of these patients showed benefit, although less than the biologic-naïve patients. Statistically significant functional improvement with apremilast, compared with placebo, was also observed (Health Assessment Questionnaire (HAQ) disability index [HAQ-DI] changes of -0.20 and -0.25 versus -0.09). Benefit was sustained in patients continuing apremilast for 52 weeks (ACR20 on the lower and higher apremilast doses in 55 and 63 percent, respectively), and responses were also maintained for secondary outcomes including skin psoriasis severity and physical function .
The most common adverse effects in the PALACE-1 trial were mild gastrointestinal symptoms, including diarrhea and nausea. Headache also occurred. Side effects usually occurred early and were self-limited. Less than 2 percent of patients receiving apremilast had weight loss that was thought to be drug-related. No significant laboratory changes were observed. Adverse events were similar over 52 weeks to those seen at 24 weeks, although diarrhea and nausea typically occurred early in therapy and were self-limited.
Patients treated with apremilast should have their weight monitored regularly, as significant and otherwise unexplained weight loss may require discontinuation of treatment . Use of apremilast has also been associated with an increase in reports of depression compared with placebo . Risks of drug use during pregnancy are unknown.
Severe peripheral arthritis/adverse prognosis — In patients presenting with severe disease who already have erosive disease and functional limitation, we suggest a TNF inhibitor as first-line therapy, rather than a conventional nonbiologic DMARD. Other biologic DMARDs (eg, secukinumab or ustekinumab) are alternatives to a TNF inhibitor. The approach in these patients is the same as that used for patients who have already had an inadequate response to nonbiologic DMARDs (see 'Resistant to nonbiologic DMARDs' below).
We prefer this approach because of the capacity of the TNF inhibitors and other biologic agents, demonstrated in multiple randomized trials and in contrast to MTX and the other conventional nonbiologic DMARDs, to limit joint damage and more rapidly restore function (see 'Resistant to nonbiologic DMARDs' below and 'TNF inhibitor use and efficacy' below and 'Secukinumab' below and 'Ustekinumab' below and 'MTX use and efficacy' above). This approach is also supported by the 2015 GRAPPA recommendations ; however, not all experts favor this approach .
Resistant to nonbiologic DMARDs — In patients whose joint counts do not improve substantially after three months of treatment with a conventional nonbiologic DMARD (eg, MTX) or who still have more than three tender and swollen joints, we recommend a TNF inhibitor, rather than sequential trials of other conventional DMARDs, unless required to use another conventional synthetic DMARD (eg, LEF) before obtaining approval for use of a biologic agent. We prefer a TNF inhibitor in this setting because of the greater experience that exists with these agents, as well as the greater number of trials providing evidence of benefit. (See 'Choice of nonbiologic DMARD and other agents' above and 'Choice of TNF inhibitor' below.)
Typically patients require up to three months of therapy to achieve a maximal response, but many respond sooner, as illustrated in multiple randomized trials with these drugs (see 'TNF inhibitor use and efficacy' below). Assessment of the treatment response should be individualized to incorporate other domains of disease activity in addition to arthritis, such as psoriatic skin involvement, dactylitis, and enthesitis, particularly in patients with moderate to severe involvement in these other domains. With respect to the musculoskeletal manifestations, a target of minimal disease activity (MDA) is desirable, but these manifestations may not be the most prominent aspects of disease in some patients. (See 'Other assessment measures' below.)
We initially add the TNF inhibitor, while continuing the conventional DMARD (eg, MTX). However, in contrast to RA, MTX generally can be discontinued in PsA patients who respond to TNF-inhibitor therapy, with one important exception, which is infliximab. Patients treated with infliximab should continue concomitant MTX, when possible, to lessen the likelihood of a reduced response to infliximab over time . Evidence from registries has not shown increased efficacy with the combination over TNF inhibitor monotherapy, although drug survival with combined treatment was increased slightly for most agents, and more markedly for patients on infliximab .
It is not uncommon for patients on TNF inhibitor monotherapy to experience sustained responses in the skin and joints, and the efficacy of TNF inhibitors for the peripheral arthritis of PsA is supported by multiple randomized trials with these agents. (See 'TNF inhibitor use and efficacy' below.)
Secukinumab and ustekinumab are alternative biologic agents that may be used in patients with contraindications to use of a TNF inhibitor (eg, patients with significant heart failure or multiple sclerosis), but in whom a TNF inhibitor would otherwise be indicated (see 'Secukinumab' below and 'Ustekinumab' below). Either of these agents may also be of benefit in patients resistant to TNF inhibitor therapy. (See 'Peripheral arthritis resistant to initial TNF inhibitor' below.)
Choice of TNF inhibitor — All five of the original TNF inhibitors (etanercept, adalimumab, infliximab, certolizumab pegol, and golimumab) are available for use in patients with PsA in the United States and in many other countries. The efficacy of the drugs for the arthritis appears comparable (see 'TNF inhibitor use and efficacy' below), and the choice of agent is based upon patient preferences for route (subcutaneous versus intravenous) and frequency of administration, regulatory and payor requirements and limitations, and potential cost to the patient. There may be a differential effect on the skin, which should be incorporated into the choice of agent made in collaboration with the patient’s dermatologist. (See "Treatment of psoriasis", section on 'Biologic agents'.)
TNF inhibitor use and efficacy — The five original TNF inhibitors and their respective dosing regimens are:
●Etanercept – 50 mg as a subcutaneous injection once weekly. Etanercept is a dimeric p75 TNF-alpha receptor Fc fragment fusion protein that binds TNF. An initial dose of 50 mg twice weekly for the first three months of therapy may be used in patients requiring treatment for moderate to severe psoriatic skin disease.
●Infliximab – 5 mg/kg administered by intravenous infusion at zero, two, and six weeks, followed by 5 mg/kg every eight weeks thereafter. It may be given either with or without MTX. Infliximab is a human / mouse chimeric anti-TNF-alpha antibody.
●Adalimumab – 40 mg subcutaneously once every two weeks. Adalimumab is a human monoclonal anti-TNF antibody.
●Golimumab – 50 mg subcutaneously once monthly. Golimumab is a human monoclonal anti-TNF antibody.
●Certolizumab pegol – Initial dose of 400 mg (administered as two 200 mg injections subcutaneously), with this dose repeated two and four weeks after the initial dose; maintenance with 200 mg once every other week, but may alternatively treat with 400 mg every four weeks. Certolizumab pegol is a pegylated Fab fragment of a humanized anti-TNF monoclonal antibody.
Screening for latent tuberculosis (TB) prior to beginning therapy with anti-TNF agents is necessary, and those with evidence of disease usually require prophylactic antituberculous therapy (see "Treatment of latent tuberculosis infection in HIV-uninfected adults"). We avoid TNF inhibitors in patients with first-degree relatives with multiple sclerosis.
The efficacy of the TNF inhibitors in patients with PsA has been well-documented in meta-analyses involving several of the agents  and in multiple clinical trials with all of the agents, including etanercept [46-49], infliximab [12,50-54], adalimumab [55-60], golimumab [61,62], and certolizumab pegol [63,64], compared with placebo. In one retrospective analysis, monotherapy with a TNF inhibitor was superior to MTX monotherapy after controlling for multiple variables . Benefits in trials included reduced activity of arthritis, with ACR20 responses in 50 to 65 percent of patients within three months; reduced radiographic progression; and improved physical function and health-related quality of life measures. In long-term follow-up studies, benefit is maintained in most patients who have responded to therapy. Enthesitis, dactylitis, and cutaneous findings also improved in TNF inhibitor-treated patients. (See 'Enthesitis and dactylitis' below.)
Higher initial doses of etanercept (50 mg twice weekly for 12 weeks, then once weekly) than are required for the joint disease may be of benefit for treatment of the skin manifestations. (See "Treatment of psoriasis", section on 'Etanercept'.)
Sustained benefit from these drugs has been shown among patients with PsA studied using several drug registries and several other studies [66-71]. As an example, in the Danish registry of 764 PsA patients treated with their first TNF-alpha inhibitor in clinical practice, the median drug survival was 2.9 years. The ACR50 response rate was 45 percent. Increased CRP at baseline was associated both with good treatment responses and with continued treatment .
In addition to improvement in clinical signs and symptoms, these agents also reduce radiographic progression of disease, as indicated by the data from the individual trial. A meta-analysis of five randomized trials involving 1110 patients found that significantly fewer patients with PsA who were treated with TNF inhibitors (including etanercept, adalimumab, infliximab, and golimumab) exhibited radiographic disease progression at week 24 of treatment compared with patients who received placebo (15 versus 31 percent); it was uncertain whether MTX provided additional benefit .
Peripheral arthritis resistant to initial TNF inhibitor
Choice of agent
●Resistant to one TNF inhibitor – We switch to a second TNF inhibitor in patients who experience an inadequate response to the first TNF inhibitor used, rather than trying a different class of biologic agent (see 'Choice of TNF inhibitor' above and 'TNF inhibitor use and efficacy' above). Most patients achieve maximal benefit after about three to four months of therapy. We prefer to switch from one of the antibody-based agents (eg, infliximab, adalimumab, golimumab, or certolizumab) to the soluble TNF receptor (etanercept) and vice versa, although formal evidence to support or refute this strategy is lacking. For example, in patients with an inadequate response to etanercept, the second agent should be one of the other four agents, while patients on an anti-TNF antibody should switch to etanercept.
●Resistant to two TNF inhibitors – In patients who do not respond adequately to two different TNF inhibitors, we use secukinumab (see 'Secukinumab' below). Secukinumab may be given with or without MTX, and in patients with marked improvement in joint and skin disease with the addition of secukinumab an effort can be made to gradually reduce or discontinue MTX. In clinical trials, secukinumab may have greater benefit for PsA than ustekinumab, but they have not been directly compared for this indication.
●Resistant to TNF inhibitors and secukinumab – In patients without an adequate response to secukinumab, we suggest ustekinumab (see 'Ustekinumab' below). Ustekinumab may be given with or without MTX, and in patients with marked improvement in joint and skin disease with the addition of ustekinumab an effort can be made to gradually reduce or discontinue MTX.
Secukinumab — Secukinumab is administered by subcutaneous injection, usually with a loading dose of 150 mg at weeks 0, 1, 2, 3, and 4, followed by 150 mg every four weeks; it may be increased to 300 mg every four weeks in patients who continue to have active arthritis. Therapy may also be initiated without a weekly loading dose with 150 mg every four weeks from the beginning of therapy. In patients with coexistent moderate to severe plaque psoriasis, the drug can be given as 300 mg once weekly at weeks 0, 1, 2, 3, and 4, followed by 300 mg every four weeks, although some patients may only require 150 mg per dose. Patients usually achieve a maximal response within three to four months of treatment.
Patients should be screened for latent TB prior to use of this agent and should be treated appropriately, if screening positive, by initiation of anti-tuberculous therapy before starting secukinumab. (See "Diagnosis of latent tuberculosis infection (tuberculosis screening) in HIV-uninfected adults" and "Treatment of latent tuberculosis infection in HIV-uninfected adults".)
Secukinumab, is a human anti-interleukin (IL)-17A monoclonal antibody, is available for the treatment of PsA and psoriasis in the United States and a number of other countries, including those in Europe. It was shown to be effective by a number of measures for the treatment of PsA in a series of phase 3 randomized trials [73-75]. In addition, other anti-IL-17 monoclonal antibodies, including ixekizumab, which is available in the United States for the treatment of moderate to severe plaque psoriasis; and an anti-IL-17 receptor antibody, brodalumab, have also shown some benefit in patients with PsA [73-79]. (See "Treatment of psoriasis", section on 'Ixekizumab'.)
Regimens for dosing and drug administration have varied between the trials:
●In a multicenter phase 3 randomized trial involving 397 patients with active PsA, secukinumab was superior to placebo in achieving significant improvement in joint and skin symptoms and findings and in physical function and quality of life . Secukinumab (300, 150, or 75 mg administered subcutaneously) or placebo were given weekly for the first four weeks and then every four weeks. A significantly higher proportion of patients treated with secukinumab (300 and 150 mg), compared with placebo-treated patients, achieved an ACR20 response at week 24 (54, 51, and 29 versus 15 percent). Responses by weeks 12 to 16 were similar to those at week 24, and benefit was sustained at 52 weeks. The drug was well-tolerated, with similar types and frequencies of adverse events in patients treated with either the drug or placebo. Patients who were inadequate responders to TNF inhibitors demonstrated a better response to the 300 mg dose than the 150 mg dose.
●Clinical and radiographic benefit was shown in a randomized trial involving 606 patients . Patients who received secukinumab (three loading doses of 10 mg/kg, followed by subcutaneous administration of either 75 or 150 mg/dose) were significantly more likely compared with patients receiving placebo to achieve the composite clinical endpoint of an ACR20 response (50 and 51 versus 17 percent) at week 24. ACR50 and ACR70 responses were also significantly more frequent in patients receiving secukinumab (31 and 35 versus 7 percent and 17 and 19 versus 2 percent, respectively). Responses were sustained at week 52. In this trial, responses to 300 mg were more frequent than to 150 mg in patients who had prior inadequate responses to TNF inhibitors (ACR20 46 versus 30 percent, ACR50 27 versus 19 percent, and ACR70 15 versus 11 percent). Treatment with secukinumab also significantly reduced radiographic progression compared with placebo and reduced the frequency of enthesitis and dactylitis.
Another anti-IL-17 agent, brodalumab, has been studied in PsA, with some evidence of benefit . However, at least one manufacturer has discontinued their development program for this agent due to concerns about suicidal ideation and completed suicides in the clinical trials for psoriasis and PsA. The overall level of risk for suicidality associated with the anti-IL-17 agents is unknown. Additional trials will be helpful to further clarify the efficacy and safety of the individual agents.
Ustekinumab — Ustekinumab is a human monoclonal antibody to the shared p40 subunit of IL-12 and IL-23, which interferes with receptor binding to immune cells. It is commercially available for the treatment of both psoriasis and PsA and is administered by subcutaneous injection (45 mg, given initially and four weeks later, then every 12 weeks). A higher dose of ustekinumab is used for patients with coexistent moderate-to-severe plaque psoriasis weighing greater than 100 kg (220 lbs) (90 mg initially and four weeks later, followed by 90 mg every 12 weeks) [80,81]. IL-23 is important in triggering the production of IL-17, which has a role in immune regulation and in mediating joint injury. IL-23 also triggers the release of IL-22, which has been implicated in keratinocyte proliferation and new bone formation in an animal model of enthesitis . (See "Treatment of psoriasis", section on 'Ustekinumab'.)
The efficacy and safety of ustekinumab for PsA has been demonstrated in several randomized trials, which included patients who had active PsA despite having received either NSAIDs, a conventional nonbiologic DMARD, or a TNF inhibitor [83-85]. As examples:
●In the multicenter PSUMMIT 1 trial, 615 patients with active PsA despite use of an NSAID or a traditional DMARD (without prior use of a TNF inhibitor) were randomly assigned to receive either ustekinumab (90 or 45 mg) or placebo at weeks 0 and 4, followed by every 12 weeks; at week 16, patients without at least 5 percent improvement in both tender and swollen joint counts were increased to 90 mg of ustekinumab if they had been receiving 45 mg, or 45 mg of ustekinumab if they had been receiving placebo . At week 24, the primary outcome, ACR20, was achieved significantly more often by the patients receiving either 90 or 45 mg of ustekinumab compared with those receiving placebo (ACR20 in 50 and 42 versus 23 percent), and responses were maintained at week 52. Clinically and statistically significant improvement in function at week 24 was also achieved more often in the patients receiving ustekinumab (HAQ-DI increase of at least 0.3 in 48 and 48 versus 28 percent). Statistically significant improvement in psoriasis, dactylitis, and enthesitis was also noted.
No opportunistic infections (including TB), malignancies, or deaths were reported. Active therapy was discontinued by less than 2 percent of patients, and serious infections (all after week 24) included two patients with cholecystitis and one each with salpingitis, erysipelas, and a pharyngolaryngeal abscess. During the placebo phase of the trial, there was one patient on placebo who experienced angina and one on ustekinumab who had a nonfatal stroke; later in the trial, two patients on ustekinumab had myocardial infarctions.
●In another phase 3 randomized trial with a similar design to that above (the PSUMMIT 2 trial), benefit was also seen among the 58 percent of trial patients who had previously received TNF inhibitor therapy . In this multicenter trial, involving 312 patients with active PsA despite use of either traditional nonbiologic DMARDs or anti-TNF therapy, ustekinumab (initially at a dose of 45 or 90 mg at weeks 0 and 4, then every 12 weeks) was significantly more likely than placebo to result in an ACR20 response at week 24 (44 versus 20 percent). Concomitant therapy with MTX was permitted in patients on a stable dose of this agent. Significant benefit compared with placebo was seen at week 24 in the subgroup that had previously received at least one TNF inhibitor (ACR20 in 36 versus 15 percent). Improvement in function was also seen at week 24 (HAQ-DI change of -0.25 versus 0.00). Benefits in composite measures of disease activity and function were sustained at week 52.
Serious adverse events occurred in 5.2 percent (15 of 287) of patients treated for 60 weeks with ustekinumab (11.82 per 100 patient-years). These included serious infections, but no cases of TB and no deaths.
●Combined data from the PSUMMIT 1 and PSUMMIT 2 trials also indicated that treatment with ustekinumab resulted in a statistically significant reduction of radiographic progression of joint injury compared with placebo from baseline to week 24 (modified van der Heijde-Sharp score increase of 0.4 versus 1.0) . Inhibition of progression was maintained at week 52.
AXIAL DISEASE — The choice of therapy for axial disease (ie, involving the sacroiliac joints and spine) is based upon the severity of disease and the patient’s response to treatment. Patients with mild symptoms may be effectively treated by use of a nonsteroidal antiinflammatory drug (NSAID) (see 'Mild arthritis/NSAIDs' above), while patients with moderate to severe arthritis or who are resistant to NSAIDs alone are usually treated with a biologic disease-modifying antirheumatic drug (DMARD) such as a tumor necrosis factor (TNF) inhibitor.
Treatment choices are also be influenced by the need to treat psoriatic skin and nail disease and psoriatic peripheral arthritis, enthesitis, and dactylitis; comorbidities; patient goals and preferences regarding routes of drug administration, needed rapidity and completeness of response, and cost of treatment; and regulatory and insurance requirements.
Use of the TNF inhibitors for axial disease in patients with psoriatic arthritis (PsA) is supported by evidence of benefit for axial spondyloarthritis in trials involving patients with ankylosing spondylitis  (see "Assessment and treatment of ankylosing spondylitis in adults"), as well as by expert opinion [16,17,24]. Conventional nonbiologic DMARDs have not been shown to be effective for controlling either symptoms or radiographic disease progression of sacroiliac or spinal arthritis.
Mild axial symptoms — In patients with mild symptoms of axial disease, which includes patients with inflammatory back pain that does not interfere with function, we suggest the use of NSAIDs in antiinflammatory dose regimens (eg, naproxen 375 to 500 mg twice daily, indomethacin 100 to 150 mg daily in divided doses, celecoxib 200 mg twice daily). NSAIDs can lessen pain and stiffness in spondylitis, although support for their use for axial manifestations of PsA is based upon their demonstrated benefit in patients with ankylosing spondylitis, expert opinion, and clinical experience [1,2,24,25,87]. (See "Assessment and treatment of ankylosing spondylitis in adults".)
Moderate to severe axial disease — In patients with axial symptoms that do not respond adequately to treatment with NSAIDs, such as those with prolonged morning stiffness and severe pain, interfering with function, we recommend a TNF inhibitor rather than a traditional nonbiologic DMARD, as the latter have been shown to be ineffective for spondylitis. The choice of agent and dosing are the same as those used for peripheral arthritis. (See 'Choice of TNF inhibitor' above and 'TNF inhibitor use and efficacy' above and "Assessment and treatment of ankylosing spondylitis in adults", section on 'Tumor necrosis factor alpha antagonists'.)
Severity of spondylitis is often assessed by the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) (calculator 1). Spondylitis is considered severe when the BASDAI is greater than 4. (See 'Resistant to nonbiologic DMARDs' above.)
Axial disease resistant to initial TNF inhibitor — In patients with axial symptoms that do not respond adequately to initial therapy with a TNF inhibitor, we use the same approach described for peripheral arthritis, switching to a second TNF inhibitor and, if that is inadequate, to an alternative biologic agent such as secukinumab or ustekinumab. (see 'Peripheral arthritis resistant to initial TNF inhibitor' above).
Two phase 3 randomized trials, named MEASURE 1 and 2, have shown a clear benefit of the interleukin (IL)-17 blocker secukinumab, compared with placebo, in ankylosing spondylitis , providing evidence of benefit for this agent for spondyloarthritis, although direct evidence for the axial manifestations in PsA is lacking. There are limited data supporting the use of the IL-12/23 inhibitor ustekinumab in patients with spondylitis; the trials have generally been limited to patients with ankylosing spondylitis. (See "Assessment and treatment of ankylosing spondylitis in adults" and "Assessment and treatment of ankylosing spondylitis in adults", section on 'Switching to a second TNF antagonist'.)
ENTHESITIS AND DACTYLITIS — Enthesitis and dactylitis often benefit from the therapies being used to treat other clinical manifestations.
Enthesitis — In patients with enthesitis, which often affects the plantar fascia and the Achilles tendon insertion, we suggest initial treatment with nonsteroidal antiinflammatory drugs (NSAIDs) (see 'Mild arthritis/NSAIDs' above). Local measures, including physical therapy and local glucocorticoids, are sometimes beneficial, but their use has not been systematically evaluated in patients with psoriatic arthritis (PsA).
In patients in whom NSAIDs, local measures, and treatments for other manifestations are insufficient to control the inflammation, particularly those with functional limitation due to enthesitis, we suggest biologic agents (eg, a tumor necrosis factor [TNF] inhibitor), rather than conventional nonbiologic disease-modifying antirheumatic drugs (DMARDs). There is no evidence that the traditional DMARDs work for this condition, and most of the biologic DMARDS used for peripheral arthritis have also been reported to be effective for enthesitis in trials in which these outcomes are also reported  (see 'TNF inhibitor use and efficacy' above and 'Secukinumab' above and 'Ustekinumab' above). This approach is consistent with expert opinion and our clinical experience [17,24].
Dactylitis — Dactylitis, or inflammation of the whole digit, may respond to NSAIDs and some traditional DMARDs (eg, methotrexate [MTX] 15 to 25 mg once weekly). If it is severe, affecting a number of digits or interfering with function, biologic DMARDs are usually indicated, as in patients with enthesitis, as improvements in dactylitis are reported as secondary outcomes in the randomized trials of these agents  (see 'TNF inhibitor use and efficacy' above and 'Secukinumab' above and 'Ustekinumab' above). Glucocorticoid injections are sometimes used, but their efficacy has been examined in a systematic fashion.
ROLE OF GLUCOCORTICOIDS — Use of oral glucocorticoids in patients with psoriatic arthritis (PsA) should generally be avoided, since their use is associated with an increased chance of developing erythroderma or pustular psoriasis; in addition, there appears to be interference with the effect of other drugs [12,91]. Rarely, oral glucocorticoids are prescribed for patients with severe flares unresponsive to conventional or biologic disease-modifying antirheumatic drugs (DMARDS). It is important, however, to taper the glucocorticoids slowly and with close observation in these patients to help avoid development of erythroderma or pustular psoriasis. In patients requiring systemic glucocorticoids, such as oral prednisone, the lowest dose necessary should be employed.
Injection of glucocorticoids into tendon insertions should not be performed because of a risk of tendon rupture, and data supporting efficacy of this approach are not available. Likewise, some clinicians inject dactylitic digits with glucocorticoids, but no data are published demonstrating efficacy.
Intraarticular glucocorticoids are sometimes used, and care should be taken in patients who require such injections to avoid injection through psoriatic plaques.
RESISTANT TO OR INTOLERANT OF STANDARD THERAPIES — Other modalities are reserved for patients with psoriatic arthritis (PsA) who either do not respond to or demonstrate toxic reactions to the usual medications. These include:
●Agents used primarily for psoriatic skin disease, such as psoralen plus ultraviolet A (PUVA) and retinoic acid derivatives (see 'Agents used primarily for skin disease' below)
●Other medications supported by very limited evidence (see 'Other therapies' below)
Alternative conventional DMARDs
Sulfasalazine — SSZ (gradually increased to 1000 mg twice daily) is used infrequently given the availability of more effective and well-tolerated agents, including methotrexate (MTX), leflunomide (LEF), the tumor necrosis factor (TNF) inhibitors, and others. Some patients require a dose of 3 g/day to obtain a therapeutic benefit. SSZ may be required prior to the use of biologics in some jurisdictions. One needs to confirm that the patient is not allergic to sulfa medications prior to initiating SSZ. Routine monitoring of laboratory tests, as in patients with rheumatoid arthritis (RA), is required as SSZ may lead to leukopenia. (See "Sulfasalazine in the treatment of rheumatoid arthritis".)
The largest study of SSZ in PsA randomly assigned 221 patients with PsA to SSZ (2 g/day) or placebo . Using the Psoriatic Arthritis Response Criteria (PsARC) to identify patients who responded to the medication, favorable responses were more frequent in the SSZ group than in the placebo group (response rates of 58 versus 45 percent).
Adverse effects may be a limiting factor for the use of SSZ. In one study, 40 percent of patients discontinued SSZ within three months . Some findings also suggest that the dose of SSZ required to control PsA may be higher than that used in RA; as a result, many patients with PsA do not tolerate SSZ, despite it being effective in some patients able to take it [92,93,97,98]. The major reasons for discontinuation of therapy are gastrointestinal side effects. In addition, the onset of drug-induced lupus and toxic epidermal necrolysis has been described in patients with psoriasis treated with SSZ [99,100].
Cyclosporine — Cyclosporine is a conventional nonbiologic DMARD, available commercially for use in psoriasis refractory to other therapies and in severe RA. Cyclosporine is used in lower doses for psoriasis and PsA than for organ transplantation. Most patients receive between 2.5 and 5 mg/kg/day, usually in divided doses. The time to response is three to four months. Renal toxicity is a limiting factor, and renal function and blood pressure need to be closely monitored (see "Cyclosporine and tacrolimus nephrotoxicity"); thus, use of cyclosporine has been largely supplanted by other more potent and safer therapies for the treatment of PsA. However, it is an effective agent for psoriatic skin disease. (See "Treatment of psoriasis", section on 'Systemic calcineurin inhibitors'.)
Evidence for the efficacy of cyclosporine for PsA includes an uncontrolled study suggesting it improved symptoms and findings of arthritis ; an open-label trial, in which it was compared with SSZ and with “usual care” (nonsteroidal antiinflammatory drugs [NSAIDs], low-dose prednisone, and analgesics), in which only very modest benefit was observed compared with the other treatments ; and a randomized trial in patients continuing MTX, to which they had had an inadequate response, in which there was improvement in the activity of the joint disease and less progression of joint damage compared with patients receiving placebo .
Azathioprine — Azathioprine is a conventional nonbiologic DMARD available commercially for use in RA; it is used only infrequently in RA, given the availability of more effective and better-tolerated agents, and there is only one randomized trial of azathioprine in PsA . This was a double-blind crossover study for 12 months, with patients randomly assigned to drug or to placebo for the first six months. Marked improvement in joint counts, grip strength, and morning stiffness was recorded in four of six patients studied, and moderate response was recorded in the other two. Complete clearing of skin lesions was noted in two of the six patients, and partial clearing was noted in four of the six. No improvement in skin or joint disease was noted in those on placebo. In our clinical experience, we have found this drug to be effective even in individuals unresponsive to other drugs. Indeed, in an uncontrolled study of 28 patients using azathioprine in our clinic, the drug was well-tolerated, and an improvement in actively inflamed joints was noted . (See "Pharmacology and side effects of azathioprine when used in rheumatic diseases".)
Agents used primarily for skin disease
Psoralen and ultraviolet light — Suggestion of benefit from PUVA therapy in PsA was noted in an uncontrolled series . Although the arthritis improved, it seemed to do so primarily in those patients whose psoriasis improved. Thus, PUVA is used primarily in patients with severe psoriasis. (See "Treatment of psoriasis", section on 'Ultraviolet light'.)
Many patients receive the combination of PUVA and a conventional DMARD. The efficacy and side effects associated with this approach are unclear. In our clinic, we have not noted any unusual adverse events combining PUVA with azathioprine, MTX, or SSZ. A group of experts has recommended that aggressive immunosuppression should not follow extensive phototherapy, especially PUVA, because of a heightened risk of malignant melanoma and of nonmelanoma skin cancer in this setting . It has not been determined whether biologic agents should be used in combination with PUVA; we avoid using them simultaneously because of concern regarding risk of cutaneous malignancy.
In addition to the usual contraindications to the use of anti-TNF therapies, a guideline from the British Society of Rheumatology also recommended caution in use of these agents in patients with prior PUVA therapy (>1000 joules), due to an increased risk of nonmelanoma skin cancer; in HIV/AIDS patients, due to a general lack of data on the safety of anti-TNF therapy in this setting; and in patients with heart failure of American Heart Association grade III or IV .
Retinoic acid derivatives — The value of the retinoic acid derivative acitretin in PsA is uncertain; we do not use these agents specifically for the treatment of arthritis, but they are sometimes used in combination with other drugs to treat psoriasis. (See "Treatment of psoriasis", section on 'Retinoids'.)
Retinoic acid derivatives take about four months to produce a response . They are given in doses of 25 to 100 mg/day, in either single or divided daily doses. Their main side effects include extreme dryness of the skin and mucous membranes and hyperlipidemia. Clinical trials were performed with etretinate, an agent that has been withdrawn from the market due to toxicity. It should be noted that retinoic acid derivatives can produce extraskeletal bone deposition and can lead to joint pain in patients with psoriasis.
Abatacept — Abatacept (CTLA4-Ig), a selective T-cell costimulation modulator used for the treatment of RA, has also shown benefit for patients with PsA in limited randomized trials. We would use abatacept in situations where other drugs have failed or have contraindications.
In a phase 2 trial, 170 patients with an inadequate response to a nonbiologic DMARD (usually MTX), a biologic agent (usually a TNF inhibitor), or both were randomly assigned to receive one of three doses of abatacept or placebo; American College of Rheumatology (ACR) composite criteria for at least 20 percent improvement (an ACR20) response was achieved significantly more often after six months of therapy among patients treated with abatacept (10 mg/kg administered intravenously in three initial doses at two-week intervals and then every four weeks) compared with those receiving placebo (48 versus 19 percent) .
The optimal treatment response was at the same dose used for RA in adults and for juvenile idiopathic arthritis (10 mg/kg). Modest improvements in skin disease were also seen, as were improvements in findings on magnetic resonance imaging of affected joints in the hands or feet. Safety profiles and drug discontinuation rates were similar among treatment and placebo groups. Additional study is needed, given the limited size and duration of the trial, and a phase 3 trial is ongoing.
Other therapies — Additional medications and other modalities have been studied, with the following observations:
●Conflicting results have been noted for colchicine treatment. Two controlled studies with random patient assignment have been reported; in one there was benefit, while in the other there was not [110,111]. A systematic review concluded that further trials were needed .
●Controlled trials of fish oil or a combination of fish and plant seed oils have not shown benefit in PsA or psoriasis, despite promising results in observational studies and measurable alterations in prostaglandin metabolism [112-114].
●Small observational studies or case reports have suggested benefit with various agents that require further evaluation. These include oral vitamin D3, bromocriptine, extracorporeal photochemotherapy, and mycophenolate mofetil [115-118].
●The addition of balneotherapy (mud packs and sulfur baths) to bathing in the Dead Sea and sun exposure provides additional benefit to that seen with bathing and sun alone in three- or four-week treatment programs, particularly for inflammatory back pain [119,120]. Benefits can still be observed in arthritis and back pain, regardless of the addition of balneotherapy, six months following treatment .
Assessment for clinical care — Patients require monitoring at regular intervals to assess the response to therapy for the psoriatic arthritis (PsA) and related morbidities and to adjust therapy based upon the treatment response. In addition, patients need regular monitoring for adverse effects of medications. Patients should be monitored more closely when new medications are being initiated, depending upon the expected response time. We monitor patients at three-month intervals when the disease is more active and under changing treatment. Stable patients may be monitored at six-month intervals. Depending upon the medication, laboratory monitoring may be required more often, sometimes at monthly intervals.
●Disease activity – Disease activity should be assessed by use of joint counts for detection of painful and swollen joints. A 66 or 68 joint count is ideal, as it can be done relatively quickly and includes the ankles and feet, which are excluded from a 28 joint count (as used, for example, to calculate a DAS28, the disease activity score in 28 joints) (see 'Other assessment measures' below). In addition to a joint count, the severity of periarticular involvement can be determined by the number of areas affected by enthesitis, with particular attention, at a minimum, to the Achilles tendon insertions and the plantar fascia in each foot, and identification and a count of the number of areas affected by dactylitis. Taken together this information is usually sufficient to provide a good estimate of the extent and severity of articular and periarticular disease in our experience. The effects of joint disease, enthesitis, and dactylitis on function should also be ascertained.
Composite measures, such as the RAPID3 (a modification of the Routine Assessment of Patient Index Data) and the DAS28-CRP (Disease Activity Score using a 28 joint count and C-reactive protein), may be helpful, but active disease may still be present in patients with a good response based upon these measures; thus, they cannot be used alone as a sufficient rationale to stop escalation of therapy. (See 'Other assessment measures' below.)
●Imaging and joint injury – In clinical practice, plain film radiography of clinically involved peripheral joints, the sacroiliac joints, and the spine are used to assess the extent and progression of disease at these sites.
●Laboratory testing – Laboratory testing depends primarily upon the specific therapeutic agents being used.
A treat-to-target approach, in which a therapeutic goal such as minimal disease activity (MDA) is targeted and treatment is adjusted at frequent and defined intervals if the target is not met, has been suggested for patients with PsA. The benefits of this strategy were supported by the first randomized trial to test this approach in PsA, a multicenter open-label trial in the United Kingdom involving 206 patients with recent-onset active PsA who had not previously received disease-modifying antirheumatic drug (DMARD) therapy . Patients who were assigned to tight control (every four week visits with pre-specified treatment escalation if MDA criteria were not met) were significantly more likely to achieve American College of Rheumatology (ACR) composite criteria for at least 20 percent improvement (an ACR20 response) at 48 weeks, compared with patients receiving standard care (as defined by their treating clinician; odds ratio [OR] 1.91, 95% CI 1.03-3.55, ACR20 in 44 versus 18 percent). Serious adverse effects occurred in 14 and 6 percent of patients in the tight control and standard care groups, respectively. Further studies are needed to identify the optimal therapeutic regimens, although these data provide evidence to further support the benefits of achieving MDA and of a treat-to-target approach . It is important to note, however, that combination therapies prescribed in this trial for some patients, including cyclosporine and combined treatment with methotrexate (MTX) and leflunomide (LEF), are not commonly prescribed in the United States for PsA.
Other assessment measures — A consensus among experts is that measures that were developed to assess the response to treatment in rheumatoid arthritis (RA) can be used for PsA . Recommended response criteria for clinical trials include the ACR20, ACR50, and ACR70 (from the ACR), as well as the DAS28 and the European League Against Rheumatism (EULAR) response criteria. However, although the DAS28 clearly distinguishes between drug- and placebo-treated patients in clinical trials, it may not be appropriate for PsA patients, many of whom have foot and distal interphalangeal (DIP) joint involvement that is not recorded in the DAS28. (See "Assessment of rheumatoid arthritis activity in clinical trials and clinical practice", section on 'Composite indices for disease activity assessment' and "Assessment of rheumatoid arthritis activity in clinical trials and clinical practice", section on 'Response criteria'.)
A detailed review of assessment methods that have been used and/or proposed for research purposes to guide development of drugs and biologic agents is beyond the scope of this topic. However, a review published in 2004 addressed the issue and highlighted the need to develop standardized approaches to assessing the activity of disease in the following domains :
●Peripheral arthritis (joint pain, tenderness, and swelling). It is essential to evaluate the feet and the DIP joints of the hands and feet because they are commonly involved in PsA.
●Clinical severity of joint damage (including restricted motion, ankylosis, or unstable joints).
●Measures of spinal mobility.
●Functional ability (disability).
A module from the Outcome Measures in Rheumatoid Arthritis Clinical Trials (OMERACT) on PsA recommended the following “core set” of domains to be included in clinical trials and observational cohort studies in PsA: peripheral joint assessment, skin assessment, patient global assessment, pain, physical function, and quality of life. The following domains were considered important but not mandatory: dactylitis, enthesitis, nail assessment, spinal assessment, radiology, physician global assessment, and acute phase reactants .
In addition to the use of measures originally developed for the study of RA are those developed more specifically for studying treatment responses in patients with PsA (eg, the Psoriatic Arthritis Response Criteria [PsARC]). A study analyzing the data from the first etanercept and infliximab randomized controlled trials demonstrated that all these indices function well in PsA. It was also shown that C-reactive protein (CRP) did not function well in PsA. Although the DAS28 functioned well, a reduction of joint count to 28 would eliminate 25 percent of the patients included in the clinical trials .
A simplified composite measure for evaluating clinical trial outcomes, the Psoriatic Arthritis Joint Activity Index (PsAJAI), has been developed based upon the data from phase III randomized trials . The PsAJAI rated responses based upon a weighted sum of 30 percent improvement in core measures with weights of 2 given to the joint count measure, the CRP laboratory measure, and the physician global assessment of disease activity measure, while 30 percent improvement in measures of pain, patient global assessment of disease activity, and the Health Assessment Questionnaire (HAQ) are given 1.
Another outcome measure to assess response in PsA in clinical trials, the Composite Psoriatic Disease Activity Index (CPDAI), was developed, based upon the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) treatment recommendation grid [25,125,126]. Numerical values were assigned to the different grades of the disease manifestations proposed by GRAPPA to up to a maximum score of 15.
Another outcome which is relevant to patients with PsA is a state of MDA, which is associated with reduced progression of damage both in an observational cohort and in drug trials [127-129]. MDA has been formally defined as follows: "A patient is classified as achieving MDA when meeting 5 of the 7 following criteria: tender joint count < or =1; swollen joint count < or =1; Psoriasis Activity and Severity Index < or =1 or body surface area < or =3; patient pain visual analogue score (VAS) < or =15; patient global disease activity VAS < or =20; health assessment questionnaire < or =0.5; tender entheseal points < or =1" . Further study is required to determine the utility of this definition of MDA as a target for treatment.
Plain film radiography, magnetic resonance imaging (MRI), and ultrasonography may provide useful information for responding to treatment and for assessing the effect of therapy on preventing joint destruction or ankylosis. There are no validated indices based upon these imaging techniques that can be recommended. However, in randomized trials, the Sharp method for evaluating radiographs and the van der Heijde modification of that method have been used successfully .
ROLE OF SURGERY — There is a paucity of reports concerning the epidemiology and efficacy of surgery in patients with psoriatic arthritis (PsA). One study of 440 patients with PsA revealed that 31 (7 percent) had undergone musculoskeletal surgery . The probability for surgery increased with disease duration. Compared with those not requiring an operative procedure, surgery patients had more active inflammation and radiological evidence of damage. However, quality of life was similar between the two groups.
Joint replacements have been performed when PsA leads to damage that limits movement and that impairs function . A review of the types of procedures performed in a cohort of patients with PsA documented the following :
●Patients with oligoarticular disease usually underwent hip or knee surgery.
●Those with distal joint disease usually had hand surgery.
●Patients with polyarticular disease underwent a variety of procedures.
It is not clear whether PsA poses an additional risk, particularly for infection; the study reported only one infection in 71 procedures .
While initial results for total hip replacement in one survey were noted to be good, there appeared to be excess bone proliferation with a decrease in mobility . We have also been disappointed with small joint arthroplasty in these patients, since they appear to fibrose around the prosthesis. In general, patients with PsA do not do as well as expected with post-reconstructive surgery .
RECOMMENDATIONS OF MAJOR ORGANIZATIONS — Our approach to treatment is generally consistent with recommendations from several major groups, although these vary somewhat depending in part upon the dates when several agents became available for use in clinical practice. These include:
●GRAPPA recommendations – These recommendations are from an international group of rheumatologists and dermatologists, the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA), which has made treatment recommendations in 2009 and 2015 for psoriasis and psoriatic arthritis (PsA) [17,25,135,136].
●EULAR treatment recommendations – The 2012 guidelines, with a 2015 update, from the European League Against Rheumatism (EULAR) are centered on five overarching principles, 10 specific recommendations, and a treatment algorithm, which was also updated in 2015 [16,24]. Specific treatment recommendations are outlined for peripheral arthritis, axial disease, dactylitis, and enthesitis, along with a consideration of comorbidities in the treatment approach.
●Canadian Rheumatology Association and Spondyloarthritis Research Consortium Canada – The Canadian Rheumatology Association, together with the Spondyloarthritis Research Consortium Canada (SPARCC), issued a revised set of treatment recommendations, which advocate for appropriate treatment depending on the patient’s clinical history and physical findings [137,138]. These recommendations include all forms of spondyloarthritis, including PsA.
PROGNOSIS — Psoriatic arthritis (PsA) was once considered a mild disease for which clinicians were reluctant to use disease-modifying antirheumatic drugs (DMARDs); however, it has since become clear that the disease is more severe than previously described . Two years after disease onset in an early disease cohort, 47 percent of patients had radiographic erosions in the hands and feet, and 56 percent were taking DMARDS. In another prospective cohort study of 100 PsA patients, the majority of patients showed progression in the number of joints involved, and 68 percent manifested radiographic progression at five years [69,140]. (See "Clinical manifestations and diagnosis of psoriatic arthritis".)
Patients appear to benefit from evaluation and treatment early in the disease by a rheumatologist [3,4]. One study involving 283 patients demonstrated that those who saw a rheumatologist within six months of onset of symptoms had better radiographic and functional outcomes compared with patients first seen by a rheumatologist at least six months after symptom onset . Similarly, another study found that patients who presented to a clinic specializing in the care of PsA within two years of diagnosis had less progression of joint damage than those who presented more than two years after diagnosis .
Some clinical and genetic risk factors for disease progression have been identified. Such information can help to prospectively identify patients who will benefit from aggressive early treatment. Severe disease may adversely affect survival.
Risk factors for progressive joint damage — A systematic literature review and consensus process has identified the following factors predicting a poor prognosis with respect to progression of peripheral joint injury :
●Increased numbers of actively inflamed joints
●Elevated erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP)
●Failure of previous medication trials
●The presence of joint damage (clinically or radiographically)
●Loss of function (by Health Assessment Questionnaire [HAQ])
●Diminished quality of life
Observations that support these findings above and that identify other prognostic factors include the following:
●Polyarticular rather than oligoarticular presentation, higher tender and swollen joint counts, a high number of joint effusions, and the damage present predict progression of clinical and radiologic damage [141-145]. Of 129 patients with PsA identified in an early arthritis clinic, the number of patients with at least one erosion in the hands or feet increased from 27 percent at baseline to 47 percent by the two-year follow-up .
●A high level of past medication use (particularly glucocorticoids) predicts progression of clinical damage [141,142].
●A low ESR generally indicates that the patient is at low risk for progression . In addition, each mm/hour increase in the ESR is associated with a 2 percent increased risk of progression of both clinical and radiological damage .
●The importance of aggressive treatment of inflammatory joint disease is supported by the finding that inflammation in a particular joint predicts progression of damage in that joint .
●Human leukocyte antigen (HLA) typing provides important predictive information, but we do not perform such testing routinely in our practice. However, with further developments, HLA testing may have greater potential to provide clinically useful prognostic information. In univariate analysis, patients who are HLA-B27-, -B39-, or -DQw3-positive are at a higher risk for progression of clinical damage; these antigens are stronger prognostic factors than the clinical variables . The presence of HLA-DR7 appears to be “protective,” predicting less progression. The best multivariate model identified the HLA-B27, when -DR7 is present, and -DQw3, when -DR7 is not present, as predicting disease progression. HLA-B39 was associated with progression in early disease . HLA-B22 is protective when all HLA antigens are added to the model .
●The presence of a variant of the interleukin (IL)-4 receptor gene is associated with greater severity of erosive disease in patients with PsA .
●The presence of antibodies to cyclic citrullinated peptides (anti-CCP) is associated with an increased prevalence of polyarthritis and of erosive joint disease in a cross-sectional study of patients with PsA . In one study of 588 patients with PsA, anti-CCP antibodies were detected in 7 percent . It is not known whether these antibodies are present in early disease and could help predict disease course or if they develop later in the illness.
Remission — Complete relief of joint tenderness and swelling may occur in a substantial minority of treated patients. As an example, among 391 patients, 69 (18 percent) achieved a remission, and nearly one-half remained free of active joint disease without continued use of medication . Periods of remission lasted an average of approximately 2.5 years. However, the majority experienced at least one relapse, after a mean duration of remission of 2.6 years. Male gender, milder disease, and less disability at presentation were each associated with a greater likelihood of achieving a remission.
Morbidity and mortality — Patients with PsA may be at increased risk for cardiovascular disease and/or death.
●In one study, there was a significant increased risk of myocardial infarction, angina, and hypertension in those with PsA versus the general population ; the increased risk was associated with severe psoriasis as well as other conventional risk factors.
●Conflicting data exist concerning the association between PsA and increased mortality [155-157]. Survival appears to have improved since the late 1970s and early 1980s, possibly related to more effective therapeutic approaches . A study of 453 patients with PsA in the United Kingdom entered in the database of a single center between 1985 and 2007 found no increase in mortality risk among this cohort compared with the general population of the United Kingdom .
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Psoriatic arthritis in adults".)
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, “The Basics” and “Beyond the Basics.” The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on “patient info” and the keyword(s) of interest.)
●Basics topic (see "Patient education: Psoriatic arthritis in adults (The Basics)")
●Beyond the Basics topic (see "Patient education: Psoriatic arthritis (Beyond the Basics)")
SUMMARY AND RECOMMENDATIONS
●Treatment of psoriatic arthritis (PsA) should be started early in disease and be coordinated between a rheumatologist, primary care clinician, and other specialists (eg, the dermatologist). Differences in response between the skin and joints and different musculoskeletal manifestations of individual therapies are common. Treatment is guided initially by an assessment of disease severity, including the degree of disease activity, damage, and impact on the patient for each clinical domain. Attention to the most severely involved region, such as axial or peripheral arthritis, should help guide therapy. (See 'Management principles and pretreatment interventions' above.)
●A treat-to–target approach should be employed for peripheral and axial arthritis, with a target of remission or minimal disease activity (MDA). Patients should undergo pretreatment screening for comorbidities and baseline testing and appropriate vaccinations before drug administration. They should be referred as needed for prevention and medical management of comorbidities, such as cardiovascular and liver disease and related risk factors. (See 'Management principles and pretreatment interventions' above.)
●Nonpharmacologic management strategies are important in the treatment of PsA in addition to drug therapy; these include physical and occupational therapy, exercise, prescription of orthotics, and education regarding the disease and about joint protection, disease management, and proper use of medications. Patients should receive assistance in weight reduction and management of cardiovascular risk factors and other comorbidities. (See 'Nonpharmacologic treatment' above.)
●In patients with mild peripheral arthritis, defined as disease involving less than four joints, no radiological evidence of damage, and minimal discomfort or functional impairment, we suggest initiating treatment with a nonsteroidal antiinflammatory drug (NSAID; eg, naproxen 375 to 500 mg twice daily, or celecoxib 200 mg twice daily) rather than starting a disease-modifying antirheumatic drug (DMARD) (Grade 2C). NSAIDs can help to control the mild inflammatory symptoms of PsA and may also lessen pain and stiffness in associated spondylitis. A concern that NSAIDs may aggravate the skin psoriasis remains unproven. An alternative that may be effective and safer for some patients, particularly those with multiple comorbidities, is apremilast (30 mg twice daily). (See 'Mild arthritis/NSAIDs' above.)
●In patients whose peripheral arthritis remains active despite the use of NSAIDs or is moderate to severe without erosions or substantial functional limitations, and who lack axial symptoms or have such symptoms as are well-controlled with NSAIDs, we suggest a conventional (small molecule) DMARD, usually methotrexate (MTX; 15 to 25 mg once weekly) rather than a biologic agent (Grade 2C). Limited randomized trial data support the use of a conventional DMARD in PsA, but its use is supported by evidence of benefit in other forms of inflammatory polyarthritis, efficacy for psoriasis, expert opinion, and clinical experience in such patients. We initiate or continue NSAIDs as bridging or adjunctive therapy as needed in patients begun on DMARDs. (See 'Choice of nonbiologic DMARD and other agents' above and 'MTX use and efficacy' above.)
●Alternatives to MTX for the peripheral arthritis include leflunomide (LEF; 20 mg daily) and sulfasalazine (SSZ), which can be tried in patients unable to take either MTX or LEF. However, unlike MTX, which is also effective for psoriasis in some patients, LEF is less helpful than MTX for the skin disease. Another alternative to MTX is apremilast, which may be particularly useful for patients who wish to avoid DMARD therapy, infusions, or injections, although only a portion of patients respond. Apremilast should not be used in patients with erosive disease, as the capacity of apremilast to prevent joint injury has not been established or adequately examined in PsA or in other forms of inflammatory arthritis. (See 'Choice of nonbiologic DMARD and other agents' above and 'Leflunomide' above and 'Apremilast' above and 'Sulfasalazine' above.)
●In patients presenting with severe disease who already have erosive disease and functional limitation, we suggest a tumor necrosis factor (TNF) inhibitor as first-line therapy, rather than a conventional nonbiologic DMARD (Grade 2B). Another biologic DMARD (eg, secukinumab or ustekinumab) is an alternative to a TNF inhibitor in such patients. We prefer this approach because of the capacity of the TNF inhibitors and other biologic agents, demonstrated in multiple randomized trials and in contrast to MTX and the other conventional nonbiologic DMARDs, to limit joint damage and more rapidly restore function. (See 'Severe peripheral arthritis/adverse prognosis' above and 'Choice of TNF inhibitor' above and 'TNF inhibitor use and efficacy' above.)
●In patients whose joint counts do not improve substantially after three months of treatment with a conventional nonbiologic DMARD (eg, MTX), or who still have more than three tender and swollen joints, we recommend a TNF inhibitor rather than sequential trials of other conventional DMARDs (Grade 1B). The choice of the agent is based upon patient preferences for route (subcutaneous versus intravenous) and frequency of administration, regulatory and payor requirements and limitations, and potential cost to the patient. (See 'Resistant to nonbiologic DMARDs' above and 'Choice of TNF inhibitor' above and 'TNF inhibitor use and efficacy' above.)
●In patients with peripheral arthritis who experience an inadequate response to an initial TNF inhibitor, we use a second TNF inhibitor rather than trying a different class of biologic agent. We prefer to switch from one of the antibody-based agents (eg, infliximab, adalimumab, golimumab, or certolizumab) to the soluble TNF receptor (etanercept) and vice versa. (See 'Choice of agent' above.)
●In patients with peripheral arthritis who do not respond adequately to two different TNF inhibitors, we use an alternative biologic agent rather than another TNF inhibitor. We prefer secukinumab (administered by subcutaneous injection, usually with a loading dose of 150 mg given at weeks 0, 1, 2, 3, and 4, followed by 150 mg every four weeks; it may be increased to 300 mg every four weeks in patients who continue to have active arthritis). In patients without an adequate response to secukinumab, we use ustekinumab (by subcutaneous injection, 45 mg, given initially and four weeks later, then every 12 weeks, with a higher dose of 90 mg for patients with coexistent moderate-to-severe plaque psoriasis weighing greater than 100 kg [220 lbs] initially and four weeks later, followed by 90 mg every 12 weeks). Either of these agents may be given with or without MTX. (See 'Choice of agent' above and 'Secukinumab' above and 'Ustekinumab' above.)
●In patients with mild symptoms of axial disease, which includes patients with inflammatory back pain that does not interfere with function, we suggest NSAIDs in antiinflammatory dose regimens (eg, naproxen 375 to 500 mg twice daily, indomethacin 100 to 150 mg daily in divided doses, celecoxib 200 mg twice daily), rather than a biologic agent (Grade 2B). (See 'Mild axial symptoms' above.)
●In patients with axial symptoms that do not respond adequately to treatment with NSAIDs, such as those with prolonged morning stiffness and severe pain, interfering with function, we recommend a TNF inhibitor rather than a traditional nonbiologic DMARD, as the latter have been shown to be ineffective in spondylitis (Grade 1B). The choice of agent and dosing are the same as those used for peripheral arthritis. (See 'Resistant to nonbiologic DMARDs' above and 'Choice of TNF inhibitor' above and 'TNF inhibitor use and efficacy' above.)
●In patients with axial symptoms that do not respond adequately to initial therapy with a TNF inhibitor, we use the same approach described for peripheral arthritis, switching to a second TNF inhibitor and, if that is inadequate, to an alternative biologic agent such as secukinumab or ustekinumab. (See 'Peripheral arthritis resistant to initial TNF inhibitor' above.).
●In patients with enthesitis or dactylitis, a response is often seen with medications used for other manifestations of PsA. In patients with enthesitis causing functional impairment who do not respond to NSAIDs and local therapy, we use a biologic agent, initially a TNF inhibitor. In patients with dactylitis who do not respond to NSAIDS, a response to a conventional DMARD (eg, MTX 15 to 25 mg once weekly) is sometimes seen, but if a conventional nonbiologic DMARD is inadequate patients should be treated with a biologic agent (eg, a TNF inhibitor). (See 'Enthesitis and dactylitis' above and 'Enthesitis' above and 'Dactylitis' above.)
●Use of oral glucocorticoids in patients with PsA should be avoided, and when required (eg, for severe flares), the dose should be the minimum needed, since their use is associated with an increased chance of developing erythroderma or pustular psoriasis; in addition, there appears to be interference with the effect of other drugs. It is important, however, to taper the glucocorticoids slowly and with close observation for the development of erythroderma or pustular psoriasis. Intraarticular glucocorticoids are sometimes used, and care should be taken in patients who require such injections to avoid injection through psoriatic plaques. (See 'Role of glucocorticoids' above.)
●PsA has variable disease expression; a significant proportion of patients may develop destructive and potentially disabling disease. Factors predicting a poor prognosis include a higher number of actively inflamed joints, an elevated erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP), failure of previous medication trials, the presence of joint damage, loss of function, and diminished quality of life. (See 'Prognosis' above.)
●Clinical monitoring of disease should include joint counts that assess both the upper and lower extremities, and the number of areas involved by enthesitis and by dactylitis. In clinical practice, plain film radiography of clinically involved peripheral joints, the sacroiliac joints, and the spine are used to assess the extent and progression of disease at these sites. (See 'Assessment for clinical care' above.)
- Bruce IN, Gladman DD. Psoriatic arthritis: recognition and management. BioDrugs 1998; 9:271.
- Cuéllar ML, Citera G, Espinoza LR. Treatment of psoriatic arthritis. Baillieres Clin Rheumatol 1994; 8:483.
- Haroon M, Gallagher P, FitzGerald O. Diagnostic delay of more than 6 months contributes to poor radiographic and functional outcome in psoriatic arthritis. Ann Rheum Dis 2015; 74:1045.
- Gladman DD, Thavaneswaran A, Chandran V, Cook RJ. Do patients with psoriatic arthritis who present early fare better than those presenting later in the disease? Ann Rheum Dis 2011; 70:2152.
- Coates LC, Fransen J, Helliwell PS. Defining minimal disease activity in psoriatic arthritis: a proposed objective target for treatment. Ann Rheum Dis 2010; 69:48.
- Coates LC, Navarro-Coy N, Brown SR, et al. The TICOPA protocol (TIght COntrol of Psoriatic Arthritis): a randomised controlled trial to compare intensive management versus standard care in early psoriatic arthritis. BMC Musculoskelet Disord 2013; 14:101.
- Coates LC. Treating to target in psoriatic arthritis. Curr Opin Rheumatol 2015; 27:107.
- Kavanaugh A, van der Heijde D, Beutler A, et al. Radiographic Progression of Patients With Psoriatic Arthritis Who Achieve Minimal Disease Activity in Response to Golimumab Therapy: Results Through 5 Years of a Randomized, Placebo-Controlled Study. Arthritis Care Res (Hoboken) 2016; 68:267.
- Coates LC, Moverley AR, McParland L, et al. Effect of tight control of inflammation in early psoriatic arthritis (TICOPA): a UK multicentre, open-label, randomised controlled trial. Lancet 2015; 386:2489.
- Johnsson H, McInnes IB, Sattar N. Cardiovascular and metabolic risks in psoriasis and psoriatic arthritis: pragmatic clinical management based on available evidence. Ann Rheum Dis 2012; 71:480.
- Di Minno MN, Peluso R, Iervolino S, et al. Weight loss and achievement of minimal disease activity in patients with psoriatic arthritis starting treatment with tumour necrosis factor α blockers. Ann Rheum Dis 2014; 73:1157.
- Goodfield M. Skin lesions in psoriasis. Baillieres Clin Rheumatol 1994; 8:295.
- Griffiths CE. Therapy for psoriatic arthritis: sometimes a conflict for psoriasis. Br J Rheumatol 1997; 36:409.
- Willkens RF, Williams HJ, Ward JR, et al. Randomized, double-blind, placebo controlled trial of low-dose pulse methotrexate in psoriatic arthritis. Arthritis Rheum 1984; 27:376.
- Sarzi-Puttini P, Santandrea S, Boccassini L, et al. The role of NSAIDs in psoriatic arthritis: evidence from a controlled study with nimesulide. Clin Exp Rheumatol 2001; 19:S17.
- Gossec L, Smolen JS, Gaujoux-Viala C, et al. European League Against Rheumatism recommendations for the management of psoriatic arthritis with pharmacological therapies. Ann Rheum Dis 2012; 71:4.
- Coates LC, Kavanaugh A, Mease PJ, et al. Group for Research and Assessment of Psoriasis and Psoriatic Arthritis 2015 Treatment Recommendations for Psoriatic Arthritis. Arthritis Rheumatol 2016; 68:1060.
- Abel EA, DiCicco LM, Orenberg EK, et al. Drugs in exacerbation of psoriasis. J Am Acad Dermatol 1986; 15:1007.
- Eder L, Chandran V, Ueng J, et al. Predictors of response to intra-articular steroid injection in psoriatic arthritis. Rheumatology (Oxford) 2010; 49:1367.
- Rosenberg P, Urwitz H, Johannesson A, et al. Psoriasis patients with diabetes type 2 are at high risk of developing liver fibrosis during methotrexate treatment. J Hepatol 2007; 46:1111.
- Chandran V, Schentag CT, Gladman DD. Reappraisal of the effectiveness of methotrexate in psoriatic arthritis: results from a longitudinal observational cohort. J Rheumatol 2008; 35:469.
- Kingsley GH, Kowalczyk A, Taylor H, et al. A randomized placebo-controlled trial of methotrexate in psoriatic arthritis. Rheumatology (Oxford) 2012; 51:1368.
- Lie E, van der Heijde D, Uhlig T, et al. Effectiveness and retention rates of methotrexate in psoriatic arthritis in comparison with methotrexate-treated patients with rheumatoid arthritis. Ann Rheum Dis 2010; 69:671.
- Gossec L, Smolen JS, Ramiro S, et al. European League Against Rheumatism (EULAR) recommendations for the management of psoriatic arthritis with pharmacological therapies: 2015 update. Ann Rheum Dis 2016; 75:499.
- Ritchlin CT, Kavanaugh A, Gladman DD, et al. Treatment recommendations for psoriatic arthritis. Ann Rheum Dis 2009; 68:1387.
- Lindsay K, Fraser AD, Layton A, et al. Liver fibrosis in patients with psoriasis and psoriatic arthritis on long-term, high cumulative dose methotrexate therapy. Rheumatology (Oxford) 2009; 48:569.
- Kalb RE, Strober B, Weinstein G, Lebwohl M. Methotrexate and psoriasis: 2009 National Psoriasis Foundation Consensus Conference. J Am Acad Dermatol 2009; 60:824.
- Menter A, Korman NJ, Elmets CA, et al. Guidelines of care for the management of psoriasis and psoriatic arthritis: section 4. Guidelines of care for the management and treatment of psoriasis with traditional systemic agents. J Am Acad Dermatol 2009; 61:451.
- Hassan W. Methotrexate and liver toxicity: role of surveillance liver biopsy. Conflict between guidelines for rheumatologists and dermatologists. Ann Rheum Dis 1996; 55:273.
- Gottlieb A, Korman NJ, Gordon KB, et al. Guidelines of care for the management of psoriasis and psoriatic arthritis: Section 2. Psoriatic arthritis: overview and guidelines of care for treatment with an emphasis on the biologics. J Am Acad Dermatol 2008; 58:851.
- Kremer JM, Alarcón GS, Lightfoot RW Jr, et al. Methotrexate for rheumatoid arthritis. Suggested guidelines for monitoring liver toxicity. American College of Rheumatology. Arthritis Rheum 1994; 37:316.
- Kaltwasser JP, Nash P, Gladman D, et al. Efficacy and safety of leflunomide in the treatment of psoriatic arthritis and psoriasis: a multinational, double-blind, randomized, placebo-controlled clinical trial. Arthritis Rheum 2004; 50:1939.
- Scarpa R, Manguso F, Oriente A, et al. Leflunomide in psoriatic polyarthritis. J Clin Rheumatol 2002; 8:286.
- Liang GC, Barr WG. Open trial of leflunomide for refractory psoriasis and psoriatic arthritis. J Clin Rheumatol 2001; 7:366.
- Behrens F, Finkenwirth C, Pavelka K, et al. Leflunomide in psoriatic arthritis: results from a large European prospective observational study. Arthritis Care Res (Hoboken) 2013; 65:464.
- Asiri A, Thavaneswaran A, Kalman-Lamb G, et al. The effectiveness of leflunomide in psoriatic arthritis. Clin Exp Rheumatol 2014; 32:728.
- FDA NEWS RELEASE. FDA approves Otezla to treat psoriatic arthritis. http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm390091.htm (Accessed on March 31, 2014).
- Schafer PH, Parton A, Gandhi AK, et al. Apremilast, a cAMP phosphodiesterase-4 inhibitor, demonstrates anti-inflammatory activity in vitro and in a model of psoriasis. Br J Pharmacol 2010; 159:842.
- Schett G, Wollenhaupt J, Papp K, et al. Oral apremilast in the treatment of active psoriatic arthritis: results of a multicenter, randomized, double-blind, placebo-controlled study. Arthritis Rheum 2012; 64:3156.
- Kavanaugh A, Mease PJ, Gomez-Reino JJ, et al. Treatment of psoriatic arthritis in a phase 3 randomised, placebo-controlled trial with apremilast, an oral phosphodiesterase 4 inhibitor. Ann Rheum Dis 2014; 73:1020.
- Edwards CJ, Blanco FJ, Crowley J, et al. Apremilast, an oral phosphodiesterase 4 inhibitor, in patients with psoriatic arthritis and current skin involvement: a phase III, randomised, controlled trial (PALACE 3). Ann Rheum Dis 2016; 75:1065.
- Cutolo M, Myerson GE, Fleischmann RM, et al.. Long-term (52-week) results of a phase 3, randomized, controlled trial of apremilast, an oral phosphodiesterase 4 inhibitor, in patients with psoriatic arthritis (PALACE 2). Arthritis Rheum 2013; 65:S346.
- Kavanaugh A, Mease PJ, Gomez-Reino JJ, et al. Longterm (52-week) results of a phase III randomized, controlled trial of apremilast in patients with psoriatic arthritis. J Rheumatol 2015; 42:479.
- Fagerli KM, Lie E, van der Heijde D, et al. The role of methotrexate co-medication in TNF-inhibitor treatment in patients with psoriatic arthritis: results from 440 patients included in the NOR-DMARD study. Ann Rheum Dis 2014; 73:132.
- Saad AA, Symmons DP, Noyce PR, Ashcroft DM. Risks and benefits of tumor necrosis factor-alpha inhibitors in the management of psoriatic arthritis: systematic review and metaanalysis of randomized controlled trials. J Rheumatol 2008; 35:883.
- Mease PJ, Goffe BS, Metz J, et al. Etanercept in the treatment of psoriatic arthritis and psoriasis: a randomised trial. Lancet 2000; 356:385.
- Mease PJ, Kivitz AJ, Burch FX, et al. Etanercept treatment of psoriatic arthritis: safety, efficacy, and effect on disease progression. Arthritis Rheum 2004; 50:2264.
- Mease PJ, Kivitz AJ, Burch FX, et al. Continued inhibition of radiographic progression in patients with psoriatic arthritis following 2 years of treatment with etanercept. J Rheumatol 2006; 33:712.
- de Vlam K, Lories RJ, Janssen S. Sustained improvement in clinical measures of psoriatic arthritis in etanercept: 3-year results in an inception cohort. (Abstract) Ann Rheum Dis 2008; 67(suppl II):525.
- Van Den Bosch F, Kruithof E, Baeten D, et al. Randomized double-blind comparison of chimeric monoclonal antibody to tumor necrosis factor alpha (infliximab) versus placebo in active spondylarthropathy. Arthritis Rheum 2002; 46:755.
- Antoni CE, Kavanaugh A, Kirkham B, et al. Sustained benefits of infliximab therapy for dermatologic and articular manifestations of psoriatic arthritis: results from the infliximab multinational psoriatic arthritis controlled trial (IMPACT). Arthritis Rheum 2005; 52:1227.
- Antoni C, Krueger GG, de Vlam K, et al. Infliximab improves signs and symptoms of psoriatic arthritis: results of the IMPACT 2 trial. Ann Rheum Dis 2005; 64:1150.
- Kavanaugh A, Antoni CE, Gladman D, et al. The Infliximab Multinational Psoriatic Arthritis Controlled Trial (IMPACT): results of radiographic analyses after 1 year. Ann Rheum Dis 2006; 65:1038.
- Antoni CE, Kavanaugh A, van der Heijde D, et al. Two-year efficacy and safety of infliximab treatment in patients with active psoriatic arthritis: findings of the Infliximab Multinational Psoriatic Arthritis Controlled Trial (IMPACT). J Rheumatol 2008; 35:869.
- Mease PJ, Gladman DD, Ritchlin CT, et al. Adalimumab for the treatment of patients with moderately to severely active psoriatic arthritis: results of a double-blind, randomized, placebo-controlled trial. Arthritis Rheum 2005; 52:3279.
- Gladman DD, Mease PJ, Ritchlin CT, et al. Adalimumab for long-term treatment of psoriatic arthritis: forty-eight week data from the adalimumab effectiveness in psoriatic arthritis trial. Arthritis Rheum 2007; 56:476.
- Gladman DD, Mease PJ, Choy EH, et al. Risk factors for radiographic progression in psoriatic arthritis: subanalysis of the randomized controlled trial ADEPT. Arthritis Res Ther 2010; 12:R113.
- Genovese MC, Mease PJ, Thomson GT, et al. Safety and efficacy of adalimumab in treatment of patients with psoriatic arthritis who had failed disease modifying antirheumatic drug therapy. J Rheumatol 2007; 34:1040.
- Van den Bosch F, Manger B, Goupille P, et al. Effectiveness of adalimumab in treating patients with active psoriatic arthritis and predictors of good clinical responses for arthritis, skin and nail lesions. Ann Rheum Dis 2010; 69:394.
- Mease PJ, Signorovitch J, Yu AP, et al. Impact of adalimumab on symptoms of psoriatic arthritis in patients with moderate to severe psoriasis: a pooled analysis of randomized clinical trials. Dermatology 2010; 220:1.
- Kavanaugh A, McInnes I, Mease P, et al. Golimumab, a new human tumor necrosis factor alpha antibody, administered every four weeks as a subcutaneous injection in psoriatic arthritis: Twenty-four-week efficacy and safety results of a randomized, placebo-controlled study. Arthritis Rheum 2009; 60:976.
- Kavanaugh A, van der Heijde D, McInnes IB, et al. Golimumab in psoriatic arthritis: one-year clinical efficacy, radiographic, and safety results from a phase III, randomized, placebo-controlled trial. Arthritis Rheum 2012; 64:2504.
- Mease PJ, Fleischmann R, Deodhar AA, et al. Effect of certolizumab pegol on signs and symptoms in patients with psoriatic arthritis: 24-week results of a Phase 3 double-blind randomised placebo-controlled study (RAPID-PsA). Ann Rheum Dis 2014; 73:48.
- van der Heijde D, Fleischmann R, Wollenhaupt J, et al. Effect of different imputation approaches on the evaluation of radiographic progression in patients with psoriatic arthritis: results of the RAPID-PsA 24-week phase III double-blind randomised placebo-controlled study of certolizumab pegol. Ann Rheum Dis 2014; 73:233.
- Heiberg MS, Kaufmann C, Rødevand E, et al. The comparative effectiveness of anti-TNF therapy and methotrexate in patients with psoriatic arthritis: 6 month results from a longitudinal, observational, multicentre study. Ann Rheum Dis 2007; 66:1038.
- Carmona L, Gómez-Reino JJ, BIOBADASER Group. Survival of TNF antagonists in spondylarthritis is better than in rheumatoid arthritis. Data from the Spanish registry BIOBADASER. Arthritis Res Ther 2006; 8:R72.
- Heiberg MS, Koldingsnes W, Mikkelsen K, et al. The comparative one-year performance of anti-tumor necrosis factor alpha drugs in patients with rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis: results from a longitudinal, observational, multicenter study. Arthritis Rheum 2008; 59:234.
- Saad AA, Ashcroft DM, Watson KD, et al. Persistence with anti-tumour necrosis factor therapies in patients with psoriatic arthritis: observational study from the British Society of Rheumatology Biologics Register. Arthritis Res Ther 2009; 11:R52.
- Glintborg B, Østergaard M, Dreyer L, et al. Treatment response, drug survival, and predictors thereof in 764 patients with psoriatic arthritis treated with anti-tumor necrosis factor α therapy: results from the nationwide Danish DANBIO registry. Arthritis Rheum 2011; 63:382.
- Eder L, Chandran V, Schentag CT, et al. Time and predictors of response to tumour necrosis factor-alpha blockers in psoriatic arthritis: an analysis of a longitudinal observational cohort. Rheumatology (Oxford) 2010; 49:1361.
- Saougou I, Markatseli TE, Papagoras C, et al. Sustained clinical response in psoriatic arthritis patients treated with anti-TNF agents: a 5-year open-label observational cohort study. Semin Arthritis Rheum 2011; 40:398.
- Goulabchand R, Mouterde G, Barnetche T, et al. Effect of tumour necrosis factor blockers on radiographic progression of psoriatic arthritis: a systematic review and meta-analysis of randomised controlled trials. Ann Rheum Dis 2014; 73:414.
- McInnes IB, Sieper J, Braun J, et al. Efficacy and safety of secukinumab, a fully human anti-interleukin-17A monoclonal antibody, in patients with moderate-to-severe psoriatic arthritis: a 24-week, randomised, double-blind, placebo-controlled, phase II proof-of-concept trial. Ann Rheum Dis 2014; 73:349.
- Mease PJ, McInnes IB, Kirkham B, et al. Secukinumab Inhibition of Interleukin-17A in Patients with Psoriatic Arthritis. N Engl J Med 2015; 373:1329.
- McInnes IB, Mease PJ, Kirkham B, et al. Secukinumab, a human anti-interleukin-17A monoclonal antibody, in patients with psoriatic arthritis (FUTURE 2): a randomised, double-blind, placebo-controlled, phase 3 trial. Lancet 2015; 386:1137.
- Leonardi C, Matheson R, Zachariae C, et al. Anti-interleukin-17 monoclonal antibody ixekizumab in chronic plaque psoriasis. N Engl J Med 2012; 366:1190.
- Hueber W, Patel DD, Dryja T, et al. Effects of AIN457, a fully human antibody to interleukin-17A, on psoriasis, rheumatoid arthritis, and uveitis. Sci Transl Med 2010; 2:52ra72.
- Papp KA, Leonardi C, Menter A, et al. Brodalumab, an anti-interleukin-17-receptor antibody for psoriasis. N Engl J Med 2012; 366:1181.
- Mease PJ, Genovese MC, Greenwald MW, et al. Brodalumab, an anti-IL17RA monoclonal antibody, in psoriatic arthritis. N Engl J Med 2014; 370:2295.
- Full US prescribing information for Stelara (ustekinumab). http://www.stelarainfo.com/pdf/PrescribingInformation.pdf (Accessed on October 12, 2013).
- European Medicines Agency. Summary of opinion (post-authorisation) for Stelara (ustekinumab). 25 July 2013. http://www.ema.europa.eu/docs/en_GB/document_library/Summary_of_opinion/human/000958/WC500146594.pdf (Accessed on October 12, 2013).
- Sherlock JP, Joyce-Shaikh B, Turner SP, et al. IL-23 induces spondyloarthropathy by acting on ROR-γt+ CD3+CD4-CD8- entheseal resident T cells. Nat Med 2012; 18:1069.
- McInnes IB, Kavanaugh A, Gottlieb AB, et al. Efficacy and safety of ustekinumab in patients with active psoriatic arthritis: 1 year results of the phase 3, multicentre, double-blind, placebo-controlled PSUMMIT 1 trial. Lancet 2013; 382:780.
- Gottlieb A, Menter A, Mendelsohn A, et al. Ustekinumab, a human interleukin 12/23 monoclonal antibody, for psoriatic arthritis: randomised, double-blind, placebo-controlled, crossover trial. Lancet 2009; 373:633.
- Ritchlin C, Rahman P, Kavanaugh A, et al. Efficacy and safety of the anti-IL-12/23 p40 monoclonal antibody, ustekinumab, in patients with active psoriatic arthritis despite conventional non-biological and biological anti-tumour necrosis factor therapy: 6-month and 1-year results of the phase 3, multicentre, double-blind, placebo-controlled, randomised PSUMMIT 2 trial. Ann Rheum Dis 2014; 73:990.
- Kavanaugh A, Ritchlin C, Rahman P, et al. Ustekinumab, an anti-IL-12/23 p40 monoclonal antibody, inhibits radiographic progression in patients with active psoriatic arthritis: results of an integrated analysis of radiographic data from the phase 3, multicentre, randomised, double-blind, placebo-controlled PSUMMIT-1 and PSUMMIT-2 trials. Ann Rheum Dis 2014; 73:1000.
- Nash P, Lubrano E, Cauli A, et al. Updated guidelines for the management of axial disease in psoriatic arthritis. J Rheumatol 2014; 41:2286.
- Baeten D, Sieper J, Braun J, et al. Secukinumab, an Interleukin-17A Inhibitor, in Ankylosing Spondylitis. N Engl J Med 2015; 373:2534.
- Orbai AM, Weitz J, Siegel EL, et al. Systematic review of treatment effectiveness and outcome measures for enthesitis in psoriatic arthritis. J Rheumatol 2014; 41:2290.
- Rose S, Toloza S, Bautista-Molano W, et al. Comprehensive treatment of dactylitis in psoriatic arthritis. J Rheumatol 2014; 41:2295.
- Kay L, Walker D. Therapy for psoriatic arthritis: sometimes a conflict for psoriasis. Br J Rheumatol 1998; 37:234.
- Dougados M, vam der Linden S, Leirisalo-Repo M, et al. Sulfasalazine in the treatment of spondylarthropathy. A randomized, multicenter, double-blind, placebo-controlled study. Arthritis Rheum 1995; 38:618.
- Gupta AK, Grober JS, Hamilton TA, et al. Sulfasalazine therapy for psoriatic arthritis: a double blind, placebo controlled trial. J Rheumatol 1995; 22:894.
- Clegg DO, Reda DJ, Abdellatif M. Comparison of sulfasalazine and placebo for the treatment of axial and peripheral articular manifestations of the seronegative spondylarthropathies: a Department of Veterans Affairs cooperative study. Arthritis Rheum 1999; 42:2325.
- Jones G, Crotty M, Brooks P. Interventions for psoriatic arthritis. Cochrane Database Syst Rev 2000; :CD000212.
- Soriano ER, McHugh NJ. Therapies for peripheral joint disease in psoriatic arthritis. A systematic review. J Rheumatol 2006; 33:1422.
- Clegg DO, Reda DJ, Mejias E, et al. Comparison of sulfasalazine and placebo in the treatment of psoriatic arthritis. A Department of Veterans Affairs Cooperative Study. Arthritis Rheum 1996; 39:2013.
- Rahman P, Gladman DD, Cook RJ, et al. The use of sulfasalazine in psoriatic arthritis: a clinic experience. J Rheumatol 1998; 25:1957.
- Veale DJ, Ho M, Morley KD. Sulphasalazine-induced lupus in psoriatic arthritis. Br J Rheumatol 1995; 34:383.
- Jullien D, Wolkenstein P, Roupie E, et al. Toxic epidermal necrolysis after sulfasalazine treatment of mild psoriatic arthritis: warning on the use of sulfasalazine for a new indication. Arthritis Rheum 1995; 38:573.
- Mahrle G, Schulze HJ, Bräutigam M, et al. Anti-inflammatory efficacy of low-dose cyclosporin A in psoriatic arthritis. A prospective multicentre study. Br J Dermatol 1996; 135:752.
- Salvarani C, Macchioni P, Olivieri I, et al. A comparison of cyclosporine, sulfasalazine, and symptomatic therapy in the treatment of psoriatic arthritis. J Rheumatol 2001; 28:2274.
- Fraser AD, van Kuijk AW, Westhovens R, et al. A randomised, double blind, placebo controlled, multicentre trial of combination therapy with methotrexate plus ciclosporin in patients with active psoriatic arthritis. Ann Rheum Dis 2005; 64:859.
- Levy JJ, Paulus HE, Barnett EV, et al. A double-blind controlled evaluation of azathioprine treatment in the rheumatoid arthritis and psoriatic arthritis. Arthritis Rheum 1972; 15:116.
- Lee JC, Gladman DD, Schentag CT, Cook RJ. The long-term use of azathioprine in patients with psoriatic arthritis. J Clin Rheumatol 2001; 7:160.
- Perlman SG, Gerber LH, Roberts RM, et al. Photochemotherapy and psoriatic arthritis. A prospective study. Ann Intern Med 1979; 91:717.
- Kyle S, Chandler D, Griffiths CE, et al. Guideline for anti-TNF-alpha therapy in psoriatic arthritis. Rheumatology (Oxford) 2005; 44:390.
- Klinkhoff AV, Gertner E, Chalmers A, et al. Pilot study of etretinate in psoriatic arthritis. J Rheumatol 1989; 16:789.
- Mease P, Genovese MC, Gladstein G, et al. Abatacept in the treatment of patients with psoriatic arthritis: results of a six-month, multicenter, randomized, double-blind, placebo-controlled, phase II trial. Arthritis Rheum 2011; 63:939.
- Seideman P, Fjellner B, Johannesson A. Psoriatic arthritis treated with oral colchicine. J Rheumatol 1987; 14:777.
- McKendry RJ, Kraag G, Seigel S, al-Awadhi A. Therapeutic value of colchicine in the treatment of patients with psoriatic arthritis. Ann Rheum Dis 1993; 52:826.
- Peloso P, Gladman DD. Fish oils in the treatment of psoriatic arthritis: An open study (abstract). Arthritis Rheum 1992; 35(Suppl 9):S225.
- Søyland E, Funk J, Rajka G, et al. Effect of dietary supplementation with very-long-chain n-3 fatty acids in patients with psoriasis. N Engl J Med 1993; 328:1812.
- Veale DJ, Torley HI, Richards IM, et al. A double-blind placebo controlled trial of Efamol Marine on skin and joint symptoms of psoriatic arthritis. Br J Rheumatol 1994; 33:954.
- Huckins D, Felson DT, Holick M. Treatment of psoriatic arthritis with oral 1,25-dihydroxyvitamin D3: a pilot study. Arthritis Rheum 1990; 33:1723.
- Buskila D, Sukenik S, Holcberg G, Horowitz J. Improvement of psoriatic arthritis in a patient treated with bromocriptine for hyperprolactinemia. J Rheumatol 1991; 18:611.
- de Misa RF, Azaña JM, Harto A, et al. Psoriatic arthritis: one year of treatment with extracorporeal photochemotherapy. J Am Acad Dermatol 1994; 30:1037.
- Grundmann-Kollmann M, Mooser G, Schraeder P, et al. Treatment of chronic plaque-stage psoriasis and psoriatic arthritis with mycophenolate mofetil. J Am Acad Dermatol 2000; 42:835.
- Sukenik S, Giryes H, Halevy S, et al. Treatment of psoriatic arthritis at the Dead Sea. J Rheumatol 1994; 21:1305.
- Elkayam O, Ophir J, Brener S, et al. Immediate and delayed effects of treatment at the Dead Sea in patients with psoriatic arthritis. Rheumatol Int 2000; 19:77.
- Gladman DD. Is it time for treat to target in psoriatic arthritis? Lancet 2015; 386:2450.
- Gladman DD, Helliwell P, Mease PJ, et al. Assessment of patients with psoriatic arthritis: a review of currently available measures. Arthritis Rheum 2004; 50:24.
- Gladman DD, Mease PJ, Strand V, et al. Consensus on a core set of domains for psoriatic arthritis. J Rheumatol 2007; 34:1167.
- Gladman DD, Tom BD, Mease PJ, Farewell VT. Informing response criteria for psoriatic arthritis (PsA). II: Further considerations and a proposal--the PsA joint activity index. J Rheumatol 2010; 37:2559.
- Mumtaz A, Gallagher P, Kirby B, et al. Development of a preliminary composite disease activity index in psoriatic arthritis. Ann Rheum Dis 2011; 70:272.
- FitzGerald OM, Helliwell P, Mumtaz A, et al. Application of composite disease activity scores in psoriatic arthritis to the PRESTA dataset. Arthritis Rheum 2010; 62(Suppl 10):S214.
- Coates LC, Helliwell PS. Validation of minimal disease activity criteria for psoriatic arthritis using interventional trial data. Arthritis Care Res (Hoboken) 2010; 62:965.
- Coates LC, Cook R, Lee KA, et al. Frequency, predictors, and prognosis of sustained minimal disease activity in an observational psoriatic arthritis cohort. Arthritis Care Res (Hoboken) 2010; 62:970.
- Mease PJ, Heckaman M, Kary S, Kupper H. Application and modifications of minimal disease activity measures for patients with psoriatic arthritis treated with adalimumab: subanalyses of ADEPT. J Rheumatol 2013; 40:647.
- Fransen J, Antoni C, Mease PJ, et al. Performance of response criteria for assessing peripheral arthritis in patients with psoriatic arthritis: analysis of data from randomised controlled trials of two tumour necrosis factor inhibitors. Ann Rheum Dis 2006; 65:1373.
- Zangger P, Gladman DD, Bogoch ER. Musculoskeletal surgery in psoriatic arthritis. J Rheumatol 1998; 25:725.
- Lambert JR, Wright V. Surgery in patients with psoriasis and arthritis. Rheumatol Rehabil 1979; 18:35.
- Zangger P, Esufali ZH, Gladman DD, Bogoch ER. Type and outcome of reconstructive surgery for different patterns of psoriatic arthritis. J Rheumatol 2000; 27:967.
- Kammer GM, Soter NA, Gibson DJ, Schur PH. Psoriatic arthritis: a clinical, immunologic and HLA study of 100 patients. Semin Arthritis Rheum 1979; 9:75.
- Kavanaugh AF, Ritchlin CT, GRAPPA Treatment Guideline Committee. Systematic review of treatments for psoriatic arthritis: an evidence based approach and basis for treatment guidelines. J Rheumatol 2006; 33:1417.
- Kavanaugh A, Ritchlin C, Boehncke WH. Quality indicators in psoriatic arthritis. Clin Exp Rheumatol 2007; 25:98.
- Rohekar S, Chan J, Tse SM, et al. 2014 Update of the Canadian Rheumatology Association/spondyloarthritis research consortium of Canada treatment recommendations for the management of spondyloarthritis. Part I: principles of the management of spondyloarthritis in Canada. J Rheumatol 2015; 42:654.
- Rohekar S, Chan J, Tse SM, et al. 2014 Update of the Canadian Rheumatology Association/Spondyloarthritis Research Consortium of Canada Treatment Recommendations for the Management of Spondyloarthritis. Part II: Specific Management Recommendations. J Rheumatol 2015; 42:665.
- Gladman DD, Shuckett R, Russell ML, et al. Psoriatic arthritis (PSA)--an analysis of 220 patients. Q J Med 1987; 62:127.
- McHugh NJ, Balachrishnan C, Jones SM. Progression of peripheral joint disease in psoriatic arthritis: a 5-yr prospective study. Rheumatology (Oxford) 2003; 42:778.
- Gladman DD, Antoni C, Mease P, et al. Psoriatic arthritis: epidemiology, clinical features, course, and outcome. Ann Rheum Dis 2005; 64 Suppl 2:ii14.
- Gladman DD, Farewell VT. Progression in psoriatic arthritis: role of time varying clinical indicators. J Rheumatol 1999; 26:2409.
- Queiro-Silva R, Torre-Alonso JC, Tinturé-Eguren T, López-Lagunas I. A polyarticular onset predicts erosive and deforming disease in psoriatic arthritis. Ann Rheum Dis 2003; 62:68.
- Gladman DD, Farewell VT, Nadeau C. Clinical indicators of progression in psoriatic arthritis: multivariate relative risk model. J Rheumatol 1995; 22:675.
- Bond SJ, Farewell VT, Schentag CT, Gladman DD. Predictors for radiological damage in psoriatic arthritis: results from a single centre. Ann Rheum Dis 2007; 66:370.
- Kane D, Stafford L, Bresnihan B, FitzGerald O. A prospective, clinical and radiological study of early psoriatic arthritis: an early synovitis clinic experience. Rheumatology (Oxford) 2003; 42:1460.
- Cresswell L, Chandran V, Farewell VT, Gladman DD. Inflammation in an individual joint predicts damage to that joint in psoriatic arthritis. Ann Rheum Dis 2011; 70:305.
- Gladman DD, Farewell VT. The role of HLA antigens as indicators of disease progression in psoriatic arthritis. Multivariate relative risk model. Arthritis Rheum 1995; 38:845.
- Gladman DD, Farewell VT, Kopciuk KA, Cook RJ. HLA markers and progression in psoriatic arthritis. J Rheumatol 1998; 25:730.
- Rahman P, Snelgrove T, Peddle L, et al. A variant of the IL4 I50V single-nucleotide polymorphism is associated with erosive joint disease in psoriatic arthritis. Arthritis Rheum 2008; 58:2207.
- Bogliolo L, Alpini C, Caporali R, et al. Antibodies to cyclic citrullinated peptides in psoriatic arthritis. J Rheumatol 2005; 32:511.
- Taylor W, Gladman D, Helliwell P, et al. Classification criteria for psoriatic arthritis: development of new criteria from a large international study. Arthritis Rheum 2006; 54:2665.
- Gladman DD, Hing EN, Schentag CT, Cook RJ. Remission in psoriatic arthritis. J Rheumatol 2001; 28:1045.
- Gladman DD, Ang M, Su L, et al. Cardiovascular morbidity in psoriatic arthritis. Ann Rheum Dis 2009; 68:1131.
- Ali Y, Tom BD, Schentag CT, et al. Improved survival in psoriatic arthritis with calendar time. Arthritis Rheum 2007; 56:2708.
- Gladman DD. Mortality in psoriatic arthritis. Clin Exp Rheumatol 2008; 26:S62.
- Shbeeb M, Uramoto KM, Gibson LE, et al. The epidemiology of psoriatic arthritis in Olmsted County, Minnesota, USA, 1982-1991. J Rheumatol 2000; 27:1247.
- Buckley C, Cavill C, Taylor G, et al. Mortality in psoriatic arthritis - a single-center study from the UK. J Rheumatol 2010; 37:2141.