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INTRODUCTION — During the past decade, severe obesity has gained recognition as a significant health problem facing a large proportion of adults and children in the United States and increasingly worldwide [1-3]. Due to a lack of nonsurgical options for severely obese adolescents and a demonstrated safety and efficacy record in adults, there has been increasing interest in surgical procedures for weight loss ("bariatric surgery") for selected obese adolescents with severe obesity. There is insufficient evidence bearing on safety or effectiveness to recommend use of surgery for children or preadolescents at this time.
The rationale, outcomes, and indications for weight loss surgery in adolescents will be reviewed here. The management and outcomes of weight loss surgery in adults and other aspects of obesity in children and adolescents are discussed separately. (See "Bariatric operations for management of obesity: Indications and preoperative preparation" and "Bariatric surgery: Postoperative nutritional management" and "Clinical evaluation of the obese child and adolescent" and "Comorbidities and complications of obesity in children and adolescents" and "Definition; epidemiology; and etiology of obesity in children and adolescents" and "Management of childhood obesity in the primary care setting".)
RATIONALE — Children and adolescents with severe obesity are at risk for and are developing important comorbidities, including obstructive sleep apnea, diabetes, hypertension, cardiac hypertrophy, and nonalcoholic fatty liver disease (NAFLD), as well as depression and impaired quality of life [4-8]. Therefore, treatment that is targeted at obesity may treat or prevent these problems and improve long-term health outcomes. (See "Comorbidities and complications of obesity in children and adolescents".)
History of weight loss surgery — During the past 40 years, weight loss surgery has clearly been shown to produce significant and sustained reductions in body mass index (BMI), diabetes, and hypertriglyceridemia in adults. It also reduces mortality, as highlighted in a 10-year follow-up of patients undergoing Roux-en-Y gastric bypass (RYGB), adjustable gastric banding (AGB), or vertical banded gastroplasty in the Swedish Obese Subjects Study [9,10]. (See "Bariatric operations for management of obesity: Indications and preoperative preparation".)
Weight loss surgery has been performed in small groups of adolescents since the late 1970s. An analysis of representative national hospital administrative data from the United States demonstrated that between 2000 and 2003, the rate of surgical weight loss procedures in adolescents tripled to an estimated 771 procedures nationwide . Since then, case volumes have continued to increase, with an estimated 1600 procedures in 2009 .
Nonetheless, less than 1 percent of the weight loss surgery procedures in the United States are performed in adolescents. As of 2014, the majority of adult bariatric cases (>60 percent) in the United States were sleeve gastrectomy (SG) , and it is likely that this procedure is also the most commonly performed bariatric operation in adolescents .
Defining severe obesity — When evaluating the risks and benefits of surgery, an important step is to identify the group of patients that are most likely to benefit from the intervention. In adults, severe obesity is generally defined as a BMI ≥40 kg/m2. This is also the BMI threshold for consideration of surgery as proposed by an NIH consensus panel; a threshold of 35 kg/m2 is used for adults with significant current comorbidities such as diabetes . (See "Bariatric operations for management of obesity: Indications and preoperative preparation".)
In children, severe obesity is defined as a BMI that is either ≥120 percent of the 95th percentile or ≥35 kg/m2 (whichever is lower) (figure 1A-B)[16,17]. BMI ≥120 percent of the 95th percentile is higher than BMI 35 for girls older than 16 years, and for boys older than 18 years. This threshold corresponds to approximately the 99th percentile (Z-score 2.33), but is preferred because the Centers for Disease Control (CDC) growth standards are not sufficiently precise to use percentile curves at the extremes [17,18]. Using this definition, approximately 10.2 percent of girls and 8.9 percent of boys 12 to 19 years have severe obesity in the United States . These children will almost always remain in the obese range as adults, and 65 percent will have Class III obesity as adults (BMI ≥40) [20,21]. They have a significantly greater prevalence of cardiovascular risk factors as compared with children with lesser degrees of obesity, and will have more health complications and higher mortality as compared with those who developed obesity during adulthood [22-25].
Alternatives — Because of the potential risks of surgical weight loss, noninvasive approaches should always be the first-line treatment for any child or adolescent with obesity. The best established approaches are multidisciplinary, using family-based behavioral techniques to support changes in diet and physical activity, with goals of reducing caloric intake, improving the quality of the food intake, and increasing energy expenditure . Recommendations from an expert committee, endorsed by the American Academy of Pediatrics and other professional organizations, advocate a staged approach to weight management based on the child's degree of obesity and response to previous interventions [16,26].
Unfortunately, the limited data available suggest that dietary and behavioral interventions alone rarely achieve significant long-term success for individuals with severe obesity, as illustrated by the following examples:
●In a randomized study of 209 children ages 8 to 16 years, with a high degree of obesity (baseline mean BMI Z-score 2.47 (SD 0.34), those treated with a one year intensive lifestyle intervention experienced a modest -1.7 unit decrease in BMI as compared with those given routine clinical counseling (95% CI: -2.3 to -1.1 kg/m2) . Seventy-one percent of families completed the intensive weight management arm, with a slightly greater drop-out rate in the counseling control group.
●A large study examined three-year outcomes of behavioral treatment of severely obese children and adolescents in Sweden. Among severely obese young children (<10 years of age), 58 percent experienced a clinically meaningful treatment response (reduction of BMI standard deviation score by at least 0.5). However, only 2 percent of severely obese adolescents showed a clinically meaningful response. Both age and severity of obesity were found to be predictors of response to behavioral treatment of pediatric obesity, leading authors to question the value of behavioral treatment for such adolescents .
●When clinically significant weight loss is achieved through intensive lifestyle modification therapy, the improvement is rarely sustained . This was shown in a study of 192 children with severe obesity, who underwent a 6-month intensive lifestyle intervention . At the end of the intervention, the group had lost 7.58 percent of body weight, compared with 0.66 percent decrease with usual care, but the differences were no longer significant one year later.
●Obese adolescents treated with behavioral therapy (eg, those randomized to placebo with behavioral therapy, as controls in pharmaceutical studies for weight loss) have typically demonstrated <3 percent weight loss [30,31]. In addition, in a study from Sweden, adolescents with severe obesity experienced a 6 percent weight gain over five years of follow-up, an informative finding given the 100 percent study visit completion rate .
While an increasing number of obesity drugs are becoming available for adults, pharmacotherapy options for adolescents (eg, medications approved by the US Food and Drug Administration [FDA] for use in youth) are very limited, and are unlikely to be clinically useful in those with severe obesity . Orlistat is the only medication that is approved in the United States for the indication of weight loss in adolescents; it has low efficacy (placebo-subtracted BMI reduction of <1 kg/m2) . Metformin has been studied for weight loss (an off-label use) in several randomized trials, but demonstrated only modest placebo-subtracted BMI reductions of about 1.1 to 1.4 kg/m2 [33-35]. Pharmacotherapy for adults with obesity, including drugs in development, is discussed in detail in a separate topic review. (See "Obesity in adults: Drug therapy".)
TYPES OF SURGERY — The most widely performed procedures in adolescents and adults are the sleeve gastrectomy (SG; >60 percent) and roux-en-Y gastric bypass (RYGB; <30 percent) [13,14]. Far fewer adjustable gastric band (AGB; <5 percent) procedures are performed. Details of these procedures and the experience in adults are discussed in a separate topic review (see "Bariatric procedures for the management of severe obesity: Descriptions", section on 'Contemporary procedures'). Outcomes of these procedures and considerations specific to adolescents are discussed below. (See 'Outcomes' below and 'Postoperative management' below.)
Sleeve gastrectomy — The SG (also known as vertical sleeve gastrectomy) is a partial gastrectomy, in which the majority of the greater curvature of the stomach is removed, creating a tubular stomach (figure 2). The frequency of this procedure for weight loss surgery has been rapidly increasing, and it accounts for approximately 80 percent of bariatric procedures in adolescents. It was originally performed as the first part of a two-stage weight loss procedure for high risk extremely obese adults, but because it often achieves excellent weight loss outcomes, it is now often used as a stand-alone procedure . Data on very long-term outcomes is pending. (See "Bariatric procedures for the management of severe obesity: Descriptions", section on 'Sleeve gastrectomy'.)
Because SG is less complex than RYGB and has a lower theoretical risk of micronutrient deficiencies, it is an attractive option for adolescents. Additionally, if patients regain weight in the long term, the SG can be converted to a RYGB. Outcomes for weight loss and comorbidity improvement are generally excellent, although the long-term weight loss may be less than for RYGB, at least for a subset of patients . Compared with AGB, SG has the advantage of avoiding a foreign body and potential associated complications. (See 'Outcomes' below.)
SG may be a particularly appropriate choice of procedure for individuals with cognitive deficits, younger age, or other issues that might increase risk for postoperative nutritional deficiencies. However, outcomes for these special populations remain unclear because the only information is from very small case series with several years follow-up. (See 'Special populations' below.)
Roux-en-Y gastric bypass — Roux-en-Y gastric bypass (RYGB) creates a small (less than 30 mL) proximal gastric pouch that is divided and separated from the distal stomach and anastomosed to a Roux-limb of small bowel 75 to 150 cm in length (figure 3). The surgery has been the most commonly performed bariatric procedure in the United States until more recently, but now accounts for about 20 percent of procedures in adolescents. (See "Bariatric procedures for the management of severe obesity: Descriptions", section on 'Roux-en-Y gastric bypass'.)
The long-term outcomes for weight loss and comorbidity improvement are well established for RYGB, based on more than 25 years of experience with this procedure in adults. In addition, it has particularly dramatic benefits on glycemic control, which may offer some advantage for patients with type 2 diabetes . On the other hand, there are probably more risks for nutritional deficiencies compared with SG. In particular, iron sufficiency and long-term outcomes for bone health after RYGB are not well studied. (See "Medical outcomes following bariatric surgery", section on 'Diabetes mellitus'.)
Adjustable gastric band — Adjustable gastric banding (AGB) is a purely restrictive procedure that compartmentalizes the upper stomach by placing a tight, adjustable prosthetic band around the entrance to the stomach (figure 4). The US Food and Drug Administration (FDA) has approved two AGB devices for use in adults in the United States, but these devices are not FDA-approved for adolescents younger than age 18. Numerous retrospective studies of adolescents have been published with favorable results, although the weight loss achieved is probably less than for SG and RYGB (see 'Outcomes' below). Lack of FDA approval and the increasing trend for use of SG has resulted in rapidly declining use of AGB in adolescents , so that it now represents <1 percent of all adolescent bariatric procedures.
Other — In the past, the range of surgical weight loss procedures performed on adults and a few adolescents included jejunoileal bypass (a procedure associated with a high rate of malabsorptive complications), vertical banded gastroplasty, and banded gastric bypass. Due to unsatisfactory safety profiles and/or efficacy, these procedures are no longer recommended. Other procedures that cause malabsorption, such as biliopancreatic diversion, are occasionally performed on adults but are generally not recommended for adolescents due to lack of safety data in this age group and concerns about long-term nutritional complications .
MECHANISMS OF WEIGHT LOSS — Reduction of caloric intake plays an important role in the dramatic weight loss produced by bariatric surgery. However, this is only partially attributable to a reduced capacity of the stomach or pouch. Many patients report a subjective decrease in appetite and increase in postprandial satiety after surgery, which helps them maintain lower intake of food. This experience suggests that the effects of bariatric surgery on weight loss and comorbidities may have neuroendocrine mechanisms, and are entirely attributable to mechanical restriction of food intake or of malabsorption.
Emerging data suggest that alterations in neuroenteric hormones that regulate appetite and energy expenditure could contribute to changes in satiety after surgery. Several studies have demonstrated an increase in postprandial total peptide YY concentrations (both PYY and PYY3-36) after Roux-en-Y gastric bypass (RYGB) compared with lean or obese nonoperative controls [40,41]. This postprandial increase in PYY is not reported after an adjustable gastric band (AGB) [42,43]. However, a single series of 12 patients undergoing the vertical banded gastroplasty (also purely restrictive) reported an increase in fasting and postprandial PYY concentrations after surgery to levels comparable to concentrations measured in lean controls .
In addition, bile acid signaling, mediated through the farnesoid-X-receptor (FXR), appears to be integral to achieving the weight loss and beneficial metabolic effects of sleeve gastrectomy (SG) in rodent models of bariatric surgery . Studies in adults have also demonstrated a rise in circulating total bile acids after RYGB, and to a lesser degree after SG; however, no significant change was demonstrated after AGB [46,47]. Bile acids have also been shown to rise significantly in adolescents as well during the rapid weight loss phase in the first three months after SG .
Dramatic improvements in insulin resistance and diabetes occur after RYGB, even prior to any significant weight loss. These changes may in part be due to increased secretion of incretins, such as glucagon-like-peptide-1 (GLP-1) by intestinal endocrine cells after surgery. After RYGB, postprandial GLP-1 plasma levels rise dramatically compared with levels in lean and obese controls, and compared with patients undergoing AGB . Further research is needed to elucidate the mechanisms through which bariatric surgery causes this abrupt enhancement of insulin sensitivity.
PREOPERATIVE EVALUATION AND SCREENING
Screening — Recommended screening prior to surgical weight loss procedures includes evaluation for the presence and severity of coexisting diseases, as well as assessment of the patient's and family's understanding and readiness for a life-changing and often permanent procedure. Recommended screening tests and evaluations that should be completed during the evaluation are highlighted in the table (table 1). The final decision on whether to proceed with surgery must be made by the multidisciplinary team, taking into consideration both objective and subjective assessments of the patient's severity of obesity and related diseases, risk of future health problems, failure to lose weight through more conventional means, psychosocial status and support, and patient and family readiness for surgery.
A multidisciplinary approach is recommended when offering weight loss surgery to adolescents [49-51]. At a minimum, the team evaluating and caring for the candidate should include an experienced bariatric surgeon, pediatric obesity specialist, nurse, dietician, and pediatric psychologist or psychiatrist. One of these providers or an additional team member should have responsibility for coordinating each patient's care and ensuring follow-up and adherence to the prescribed medical regimen. The program also must have ready access to relevant pediatric subspecialties, including endocrinology, cardiology, gastroenterology, pulmonology, gynecology, and orthopedics, for further evaluation and/or management of specific comorbidities as needed.
Patient selection — In adults, the threshold for consideration of weight loss surgery is a body mass index (BMI) ≥40 kg/m2; a threshold of ≥35 kg/m2 is used for individuals with significant current comorbidities, such as diabetes. For adjustable banding, the threshold for adults with significant comorbidities is a BMI >30 kg/m2. (See "Bariatric operations for management of obesity: Indications and preoperative preparation".)
For adolescents, the following criteria for weight loss surgery have been recommended by a panel of experts [52,53]:
●BMI ≥35 kg/m2 and a severe comorbidity that has significant short-term effects on health (eg, moderate to severe obstructive sleep apnea [AHI >15], type 2 diabetes mellitus, pseudotumor cerebri, or severe and progressive steatohepatitis), or BMI ≥40 with more minor comorbidities. These are the same BMI thresholds used to select adults for bariatric surgery. Note that use of these fixed BMI thresholds is naturally more conservative for younger patients, in that the fixed threshold corresponds to a higher BMI percentile or Z-score in younger compared with older adolescents or adults. In particular, a BMI ≥40 represents very severe obesity in younger patients, particularly those younger than 16 years, in whom this threshold is substantially higher than the 99th percentile curve (figure 1A-B) (see 'Defining severe obesity' above). Even more conservative thresholds were used in the past [49,54].
●Physical maturity, defined as completing 95 percent of predicted adult stature based on bone age or reaching Tanner stage IV (rather than a particular age threshold). This criterion is based on theoretical concerns that rapid weight loss after Roux-en-Y gastric bypass (RYGB) might inhibit statural growth if an adolescent has not reached near adult height. There is no specific evidence that performing a bariatric procedure before this threshold is reached has adverse effects on height. Also, the concern may not be relevant for adjustable gastric band (AGB) procedures because weight loss is usually more gradual. (See "Normal puberty", section on 'Sexual maturity rating (Tanner stages)' and "The child with tall stature and/or abnormally rapid growth", section on 'Bone age'.)
●History of sustained efforts to lose weight through changes in diet and physical activity. There is no evidence that prolonged preoperative weight management programs enhance selection of patients for weight loss surgery. However, consistent attendance in such a treatment program may be a valuable indicator of the patient's ability to understand and adhere to medical and nutritional recommendations postoperatively.
These guidelines rest primarily on expert opinion and retrospectively evaluated outcomes data. There is only one randomized controlled trial in adolescents that demonstrates superiority of surgical weight loss as compared with conventional medical therapy for the severe comorbidities listed above . However, randomized controlled trials in adults with type 2 diabetes mellitus have demonstrated that bariatric surgery (including RYGB, AGB, and sleeve gastrectomy [SG]) is significantly more effective than conventional or intensive medical therapy in resolution of type 2 diabetes mellitus at one and two years postoperatively [56,57].
It should be recognized that the above criteria alone are not sufficient to select the patients who are most likely to benefit from weight loss surgery during adolescence. We recommend that the multidisciplinary team consider carefully whether the patient and family have the ability and motivation to adhere to recommended treatments pre- and postoperatively, including consistent use of micronutrient supplements. Evidence may include a history of reliable attendance at office visits for weight management and compliance with other medical needs. In addition, the team should consider whether the adolescent shows evidence of mature decision-making, with appropriate understanding of the risks and benefits of surgery, and has support but not coercion from family members.
Many experts believe that earlier surgical intervention probably is beneficial for adolescents with progressively worsening obesity (analogous to the surgical approach for cancers). This opinion is based upon indirect evidence from observational studies in adolescents and adults in which lower BMI at baseline generally predicts lower absolute BMI after surgery. Since on average, bariatric surgery results in a loss of 25 to 30 percent of BMI, treatment rendered earlier after the diagnosis of severe obesity is more likely to result in postoperative BMI values that are in the healthier ranges . No studies have directly addressed the timing of surgical intervention relative to BMI trend or age. (See 'Weight loss' below.)
Contraindications for surgical weight loss procedures in adolescents include:
●Medically correctable cause of obesity
●An ongoing substance abuse problem (within the preceding year)
●A medical, psychiatric, psychosocial, or cognitive condition that prevents adherence to postoperative dietary and medication regimens or impairs decisional capacity
●Current or planned pregnancy within 12 to 18 months of the procedure
●Inability on the part of the patient or parent to comprehend the risks and benefits of the surgical procedure
Special populations — The appropriate use of weight loss surgery for individuals with cognitive deficits or immaturity remains unclear. There is limited evidence that weight loss surgery, and SG in particular, may be safe and beneficial in patients with cognitive deficits, younger age, or other issues that might increase risk for postoperative nutritional deficiencies. Outcomes of SG for these populations are based on small case series with several years follow-up. As an example, two overlapping case series of 226 pediatric patients undergoing SG included seven patients with Prader-Willi syndrome, two with Bardet-Biedl syndrome, three with mental retardation, and one with Down syndrome [59,60]. There were no deaths and no major complications. Although the series included 74 prepubertal patients, the data collection and follow-up are insufficient to determine the safety and outcomes of SG in this younger age group. A separate study on an overlapping population included 19 children ages 5 through 8.99 years and 56 children 9 to 13.99 years . Children in both age groups experienced good linear growth during the first few years after weight loss surgery.
One contemporary study reports benefits of a narrow SG for individuals with Prader-Willi syndrome, most with two to five years of follow-up . However, more investigation is required before use of weight loss surgery for patients with Prader-Willi or other syndromes can be widely recommended [63,64]. In particular, it is unclear whether long-term durability of weight loss after SG in individuals with Prader-Willi syndrome will be achieved, and the type and frequency of adverse events is inadequately explored. (See "Clinical features, diagnosis, and treatment of Prader-Willi syndrome".)
PERIOPERATIVE SAFETY — To provide for optimum safety of the patient while hospitalized, it is important to ensure that the program also has access to pediatric anesthesiology and radiology consultants who have experience caring for individuals with severe obesity. Specialized equipment, such as computed tomography (CT), magnetic resonance imaging (MRI), and dual-energy X-ray absorptiometry (DEXA) scanners, often have weight limitations, which may preclude their use for these patients . Further, basic equipment such as operating tables, stretchers, scales, beds, and toilets that can support extreme weight ranges must be available to ensure safety of the patient and caretakers.
To prevent the development of venous thromboembolism, we recommend the use of compression boots until the patient is ambulatory. Patients at increased risk for deep vein thrombosis and thromboembolism (eg, those with severely impaired mobility or a hypercoagulable state) are often treated with low-molecular weight heparin in the perioperative period. (See "Bariatric surgery: Postoperative and long-term management of the uncomplicated patient", section on 'Venous thromboembolism' and "Bariatric operations: Perioperative morbidity and mortality", section on 'Venous thromboembolism'.)
Weight loss surgery frequently leads to an abrupt resolution of hypertension and hyperglycemia. Antihypertensive or hypoglycemic medications that were given preoperatively usually can be discontinued after surgery, and the patient should be monitored for his or her response. (See "Bariatric surgery: Postoperative nutritional management", section on 'Diet and texture progression' and "Bariatric surgery: Postoperative and long-term management of the uncomplicated patient".)
POSTOPERATIVE MANAGEMENT — Average inpatient stays range from three to four days for laparoscopic roux-en-Y gastric bypass (RYGB) and from two to three days for sleeve gastrectomy (SG). Postoperative management for patients includes strict measurement of intake and output, monitoring of drain output to evaluate for potential leak, and gradual advancement of diet from nil per os (NPO) to clear liquids to a high-protein liquid diet. (See "Bariatric surgery: Postoperative nutritional management" and "Bariatric surgery: Postoperative and long-term management of the uncomplicated patient", section on 'Postoperative care after discharge'.)
Diet — Dietary management after discharge varies with the type of surgery. After RYGB and SG, the patient advances through several stages, from high-protein shakes to gradual introduction of greater volumes and more textured and solid foods . The advancement to regular foods is slow, occurring over the first six months after surgery. For best results, the patient is encouraged to eat three to four small, high-protein meals per day and to avoid high-fat and carbohydrate foods, as these may provoke malabsorptive or dumping side effects. Supplemental fluids are encouraged to avoid dehydration (64 to 92 ounces per day of sugar-free, noncarbonated beverages). Drinks should be sugar-free to avoid dumping syndrome and weight regain through overconsumption of liquid calories. Patients also are advised to avoid drinking during meals to avoid nausea and vomiting. Some patients experience greater degrees of nausea in the first postoperative month after SG as compared with RYGB, requiring addition of anti-emetics and antinausea medications. Typically, however, this resolves over time.
Follow-up visits are typically performed at two weeks postoperatively, then 1, 3, 6, 9, and 12 months after surgery. After that, annual follow-up is recommended for monitoring of anthropometric measurements, nutritional status, residual comorbidities, and general health. Follow-up for AGB patients typically is more frequent due to the need for band adjustments. Some patients require visits every four to six weeks during the first one to two years.
General recommendations for long-term weight maintenance include:
●Drinking 8 to 12 eight-ounce servings of sugar-free liquids per day. Some providers encourage the patient to avoid or limit caffeinated or carbonated beverages, based on theoretical concerns that these substances may be detrimental after surgery, although there is little evidence to support this concern.
●Exercising 30 to 60 minutes daily.
●Eating protein first at each meal (1 g/kg of ideal body weight).
●Three to four portion-controlled meals per day, with minimal snacking between meals.
●Taking daily vitamin and mineral supplementation.
These guidelines may need to be tailored to meet an individual patient's needs if significant weight regain or too much weight loss has occurred.
Nutritional supplements — After RYGB or SG procedures, lifelong supplementation with vitamins and minerals is recommended to avoid development of nutritional complications secondary to reduced intake and/or mild malabsorption. Although SG and AGB may be associated with reduced risk for nutritional deficiencies compared with RYGB, long-term data on nutritional outcomes are still lacking. We therefore prescribe the same supplementation for all patients regardless of the bariatric procedure. As long-term data on outcomes in adolescents are collected, these initial recommendations may be modified.
After RYGB, patients should conscientiously adhere to a supplementation regimen because of risks for malabsorption of micronutrients; the recommended doses and preparations vary somewhat among practices and may be adjusted based on laboratory measures.
We prescribe the following supplements for all patients (table 2):
●Standard multivitamin with folate and iron, or prenatal vitamin if female (once or twice daily).
●Vitamin B12, 1000 micrograms orally daily, or 1000 micrograms IM monthly. In those with satisfactory levels at annual monitoring, a single annual dose of 3000 microgram IM can be considered.
●Calcium, 1200 to 1500 mg daily (measured as elemental calcium), with 800 to 1000 international units of vitamin D.
Additional supplementation may be necessary during pregnancy or as indicated by laboratory testing. If postoperative vomiting is severe, vitamin B1 (thiamine) deficiency also can rapidly develop . Vitamin B1 deficiency is particularly important to recognize early, as lasting neurologic sequelae can result if rapid replenishment of vitamin B1 is not initiated . In the author's program, vitamin B1 supplementation (50 mg orally daily) is provided during the first six months after surgery as a prophylactic measure.
After AGB, a routine multivitamin may suffice if a well-balanced, healthy diet is consumed. However, menstruating females may require additional iron supplementation, and all patients should have routine monitoring for deficiencies as described below.
Nutritional monitoring — After bariatric surgery, lifelong monitoring of nutritional status is recommended. In our practice, we measure the following parameters annually:
●Complete blood cell count with differential.
●Serum iron and ferritin.
●Red blood cell folate, serum vitamin B12, and serum homocysteine.
●Serum thiamine (vitamin B1).
●Albumin and total protein.
●Alkaline phosphatase, calcium, 25-hydroxy vitamin D, and parathyroid hormone.
●Dual energy X-ray absorptiometry (DEXA) scan, to monitor lean and fat-free mass, and bone density. This test is optional and may not be needed annually or for patients with good nutritional status.
Adjustments in nutritional supplements may need to be made if specific deficiencies emerge over time, particularly because many adolescents may be nonadherent or only partially adherent to recommended supplementation. (See "Bariatric surgery: Postoperative nutritional management", section on 'Postsurgical screening'.)
Pregnancy prevention — Severe obesity can lead to irregular menstruation, anovulation, and infertility. Conversely, surgically induced weight loss leads to resumption of ovulation and renewed fertility for some women . The effects of bariatric surgery on menstrual irregularities and anovulation in adolescents has not been established. However, in a series of 47 adolescent females who had undergone bariatric surgery during adolescence, a higher-than-expected rate of pregnancy was observed (seven pregnancies, six of which occurred between 10 and 22 months postoperatively) . Although the medical and psychosocial factors contributing to this high rate could not be addressed in this retrospective report, the high rate of pregnancy highlights the importance of addressing contraception and pregnancy prevention in all female adolescents undergoing bariatric surgery.
Pregnancy should absolutely be avoided for at least 12 to 18 months after surgery due to the rapid weight loss and potential micronutrient deficiencies, which may have adverse effects on the mother and fetus. However, long-term effects of bariatric surgery on fertility and pregnancy outcomes are generally good. (See "Fertility and pregnancy after bariatric surgery".)
The efficacy of oral contraceptives or transdermal contraceptive patches may be compromised in patients with obesity [71-73]. This is a significant concern both pre- and postoperatively, as many adolescent patients may still have a postoperative BMI >30kg/m2 despite significant weight loss after surgery. The American College of Obstetricians and Gynecologists (ACOG) recommends using non-oral forms of hormonal contraception in women who have undergone malabsorptive bariatric surgery and desire hormonal contraception. Further, use of oral contraception is associated with an increased risk of thromboembolism, which may compound the higher risk associated with obesity.
Depot medroxyprogesterone acetate is effective in overweight or obese women but has been reported to cause significant weight gain (mean of 4 to 9 kg) in overweight or obese adolescents [74,75]. In contrast, the levonorgestrel intrauterine system (Mirena, Bayer Schering Pharma, Berlin, Germany) does not cause weight gain and remains effective in overweight/obese women . It has several notable advantages that make it an optimal choice for adolescent females after bariatric surgery, including five-year efficacy, promotion of amenorrhea (which could help reduce risk of iron deficiency anemia after surgery), and option for placement at time of bariatric surgery . Therefore, we consider it a particularly valuable choice for adolescents who have undergone RYGB. However, as with all forms of hormonal contraception, adolescents should be counseled to use additional barrier protection against sexually transmitted diseases. These and other considerations about contraceptive choice are discussed separately. (See "Fertility and pregnancy after bariatric surgery".)
Adolescent females who become pregnant after weight loss surgery should be counseled about adequate macro- and micronutrient intake. At a minimum, a prenatal vitamin with folic acid and iron, 1200 to 1500 mg of calcium citrate with 800 IU vitamin D, and 500 mcg of oral vitamin B12 daily should be prescribed . Additional iron supplementation may be necessary in pregnant women after RYGB. Iron, folate, and vitamin B12 levels should be monitored during pregnancy and additional supplementation prescribed as indicated by results. Protein intake of at least 1 g/kg of ideal body weight (typically 60 to 80 grams) per day is recommended.
Weight loss — Both sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) in adolescents lead to clinically important decreases in weight and body mass index (BMI) in the majority of patients in the short to intermediate term (one to three years postoperatively). Information about long-term outcomes (longer than three years) is more limited, but the weight loss appears to be sustained, though attrition over time could bias findings. Adjustable gastric band (AGB) is a less popular choice for adolescents in the United States, possibly due to lack of US Food and Drug Administration (FDA) approval for adolescents and the relatively better weight loss from SG and RYBG.
The largest prospective study of outcomes of weight loss surgery in adolescents included 242 adolescents with severe obesity who predominantly underwent SG or RYGB at five centers in the United States with special expertise in bariatric surgery for this age group (Teen-LABS study) . The mean age of the participants was 17±1.6 years, and one-third were between 13 and 15 years of age. Among 67 participants undergoing SG, BMI decreased from 50 kg/m2 at baseline to 37 kg/m2 (a 26 percent reduction) three years postoperatively. Among 161 participants undergoing RYGB, BMI decreased from 54 kg/m2 at baseline to 39 kg/m2 (a 28 percent reduction) three years postoperatively (figure 5). At three years, weight regain to above baseline occurred in only 4 percent of participants with SG and 2 percent of those with RYGB.
Longer-term outcomes were reported in a population from one of the Teen-LABS centers, which reported outcomes for 58 individuals undergoing RYGB with more than five years' follow-up (FABS-5+ study) . At mean follow-up of 8 years, BMI had decreased from 58.5 to 41.7 kg/m2, representing a 29.2 percent decrease from baseline, but a modest increase from the average nadir BMI one year postoperatively. At long-term follow-up, 63 percent had at least moderately severe obesity (BMI ≥35 kg/m2). A separate study from Sweden described long-term outcomes after RYGB in a group of 81 adolescents with less severe obesity . Prior to surgery, the mean BMI was 45.5 kg/m2; at follow-up five years postoperatively the mean BMI was 32.3 kg/m2, and 28 percent had BMI ≥35 kg/m2. Together, these studies suggest that surgical intervention in patients with moderate obesity has better absolute BMI outcomes than for patients with severe obesity, supporting the notion that early intervention may be beneficial.
Previous studies reporting outcomes of weight loss surgery in adolescents have utilized a retrospective design and report short- to intermediate-term outcomes (outcomes measured from 1 to 6.3 years after surgery). A few studies have reported small numbers of patients 10 or more years after their procedure. In most of these long-term studies, a substantial number of subjects were lost to follow-up, which could bias findings.
Despite these limitations, these studies confirm that clinically significant and durable weight loss can be achieved in most patients by either SG [59,60,80] or RYGB [81-84], while AGB is probably somewhat less effective, with slower and less weight loss [55,85-90]. As an example, a meta-analysis of 37 studies reported substantial weight loss with any of these procedures. Mean BMI loss was 16.6 kg/m2 for RYGB, 14.1 kg/m2 for SG, and 11.6 kg/m2 for AGB; these differences were not statistically significant, and comparison of outcomes was limited by lack of randomization among the procedures and different lengths of follow-up .
Of note, the nadir postoperative BMI tends to be lower in patients with less severe obesity preoperatively as compared with those with more severe obesity, although the percent BMI change is similar. In a large series of patients from a single center undergoing RYGB, the mean nadir postoperative BMI was 31, 38, and 47 kg/m2 for patients with starting BMIs between 40 to 54, 55 to 65, and >65 kg/m2, respectively .
It is not clear to what degree weight loss will be sustained in adolescents and whether comorbid conditions will recur if significant weight is regained in long-term follow-up. Two studies with 4 to 10 years of follow-up suggest that 10 to 15 percent of patients regain significant weight after RYGB procedures [81,92]. Specific predictors of weight regain after surgical weight loss procedures are unknown for adults and adolescents. There is still insufficient information to directly compare the long-term weight loss outcomes of SG with those for RYGB or AGB in adolescents.
Comorbidity improvement — Weight loss surgery results in resolution of or improvement in most obesity-related diseases in both adults and adolescents. The most dramatic improvements have been seen in insulin resistance, triglyceride levels, diabetes, obstructive sleep apnea, nonalcoholic fatty liver disease, and renal function, as well as depression and quality of life [5,38,58,85,89,93-99]. In the Teen-LABS study described above, type 2 diabetes resolved in 95 percent of the participants who had the condition at baseline, and other comorbidities also resolved in most patients, including prediabetes, elevated blood pressure, and dyslipidemia (figure 6) . Similar improvements were seen in two studies with more than five-year outcomes, demonstrating long-term durability of these important metabolic effects of surgery [32,58]. Another Teen-LABS analysis highlighted kidney function, a seldom reported outcome after bariatric surgery. Among severely obese adolescents with impaired kidney function at baseline (eGFR <90 ml/min/1.73 m2), mean eGFR improved from 76 ml/min/1.73 m2 to 102 ml/min/1.73 m2 at three years follow-up (p<0.0001) . Similarly, participants with evidence of kidney injury (albuminuria) at baseline demonstrated a significant improvement of albumin to creatinine ratio (ACR); geometric mean of ACR was 74 mg/g at baseline, and decreased to 17 mg/g at three years (p<0.0001). Those with normal renal function and no albuminuria at baseline remained stable throughout the study period. In the same cohort, there were substantial improvements in functional mobility, as demonstrated by a 400-meter walk test, and in musculoskeletal pain . The metabolic improvements are consistent with the observation that weight loss after surgery is accompanied by a significant reduction in body fat (from 51 percent to 37 percent in one series) with relative preservation of lean body mass . One study also showed improvements in obesity-associated cardiac abnormalities, including concentric left ventricular hypertrophy and diastolic function, as measured by echocardiogram performed before and 10 ± 3 months after RYGB surgery .
Bariatric surgery leads to improvements in psychosocial functioning, at least in the short term. In the Teen-LABS study, quality of life improved substantially after weight loss surgery . In a pilot study of 16 adolescents undergoing RYGB, a substantial reduction in depressive symptoms occurred over the first postoperative year, accompanied by improvements in measures of health-related quality of life and self-concept (social, appearance, and close-friendship) . However these improvements decelerated in the second postoperative year, accompanied by modest weight regain and slight increase in depressive symptoms, as well as declines in measures of health related quality of life, including social, body esteem, physical comfort and total domains, as well as self-concept. Another study of 37 adolescents undergoing RYGB showed that anxiety and depression symptoms were higher at baseline than gender-specific norms, but declined significantly by four months after surgery . There was no change in anger and disruptive behavior symptoms. Larger and more long-term studies are required to better understand the impact of bariatric surgery on psychosocial functioning in adolescents.
Short-term complications — Short-term complications (<30 days after surgery) are generally similar to those in adults. Complications after RYGB include intestinal leakage at anastomotic sites, wound infections, pulmonary embolus, gastrojejunal strictures requiring endoscopic dilatation, small bowel obstruction, gastrogastric fistula formation, and symptomatic cholelithiasis . Complications of SG also include leak at the staple line. SG patients also may experience heightened and more protracted nausea in the first month postoperatively, compared with patients undergoing RYGB. Complications of AGB procedures in adolescents and adults include band slippage requiring repositioning, gastric obstruction, and esophageal or gastric pouch dilatation .
Among the 242 participants in the Teen-LABS study cited above there were 20 major complications within 30 days of surgery (8 percent overall; RYGB 9 percent, SG 5 percent and AGB 7 percent) . Major complications included reoperation for bowel obstruction/bleeding leak or sepsis, postoperative bleeding requiring transfusion, or intraoperative splenic injury. There were 47 minor complications (15 percent overall; RYGB 17 percent, SG 12 percent and AGB 7 percent). Most major and minor complications occurred prior to discharge from the hospital, and there were no deaths. Thus, short-term complications appear to be somewhat lower for patients undergoing SG as compared with those undergoing RYGB. Although AGB appears to offer a short-term advantage in complication rates, the procedure also is associated with greater long-term risks for revisional surgery, as described below. (See 'Long-term complications' below.)
Several studies performed in the United States suggest weight loss surgery may be somewhat safer in adolescents as compared with adults . The reason for this is unknown, but the observation may reflect a better state of health among individuals undergoing surgery at a young age.
●A national analysis of weight loss surgery using utilization codes revealed no perioperative mortality and a significantly shorter length of stay in adolescents as compared with adults . Five percent of adolescent patients had major complications, but the majority (78.3 percent) was respiratory in nature.
●A large study comparing the perioperative outcomes of weight loss surgery between 309 adolescents and 55,192 adults (>18 years) found that the overall 30-day complication rate was significantly lower in adolescents (5.5 percent) as compared with adults (9.8 percent). There was no difference in observed/expected mortality ratios. The 30-day morbidity and mortality rates for adolescents following restrictive procedures (AGB and vertical banded gastroplasty) were nil, compared with the morbidity rate of 4.3 percent for laparoscopic RYGB, and 7.6 percent for open RYGB .
Long-term complications — Long-term complications of weight loss surgery in adolescents are primarily nutritional. In particular, patients are at risk for deficiencies of iron, vitamin B12, vitamin D, and thiamine. In a study that focused on adolescents and young adults undergoing RYGB with long-term outcomes (FABS-5+ study cited above), low ferritin levels were noted in 63 percent, mild anemia in 46 percent, elevated parathyroid hormone in 45 percent, and vitamin B12 deficiency in 16 percent ; the subjects' adherence to routinely prescribed nutritional supplements was not reported. In the Teen-LABS study, the prevalence of low ferritin levels rose from 5 percent at baseline to 57 percent three years after surgery . The prevalence of low ferritin levels increased after either RYGB or SG, but was particularly common after RYGB. Vitamin D insufficiency (indicated by low levels of 25-hydroxyvitamin D) was noted in 42 percent of participants, but this rate was only slightly and not significantly increased over baseline. Vitamin B12 deficiency rose after both RYGB and AGB, while vitamin A deficiency increased from 6 to 16 percent in only those who had undergone RYGB. These observations suggest that nutritional deficiencies are common in this population, particularly among adolescents undergoing RYGB, and need to be monitored and managed over the long term.
Because these nutritional deficiencies are common after weight loss surgery, lifelong vitamin and mineral supplementation is imperative. However, adherence to supplementation regimens among adolescents may be poor; one study reported that only 13 percent of adolescents were adherent to all prescribed nutritional supplementation [81,92]. The specific recommendations are outlined above. (See 'Nutritional supplements' above.)
RYGB is associated with reduced bone mass in adults and is probably caused by a combination of reduced mechanical load, changes in adipogenic hormones, and nutritional deficiencies. In adolescents, reduced bone mass has been noted two years after weight loss surgery, but remains appropriate for the individual's age and new body weight . As in adults, long-term studies are lacking, and the clinical implications of these changes are unclear. However, these findings underscore the importance of supplementing and monitoring vitamin D and calcium after weight loss surgery. (See 'Nutritional supplements' above and 'Nutritional monitoring' above.)
Recurrent episodes of severe postprandial hypoglycemia may develop after RYGB and SG in some adult patients [108-110]. The mechanism of these hypoglycemic episodes is not known but may result in part from increased incretin secretion after surgery, pancreatic islet cell hyperplasia, and inappropriate postprandial hyperinsulinemia . Although a similar syndrome in adolescents after RYGB has not yet been reported in the literature, at least one adolescent patient in the authors' weight loss surgery program developed severe postprandial hyperinsulinemia after RYGB. Dietary management by providing small meals with relatively low content of carbohydrates was successful in controlling symptoms. Therefore, it is important to ask adolescents about symptoms that may suggest postprandial hypoglycemia during follow-up care after weight loss surgery.
Cholelithiasis is a common complication of any type of weight loss surgery. In the Teen-LABS study, cholecystectomy was required within three years in 8.6 percent of patients (9.9 percent for RYGB and 5.1 percent for SG) . An additional 5 percent of participants required other abdominal operations, including lysis of adhesions, gastrostomy, or ventral or internal hernia repair.
AGB is associated with a substantial risk of complications requiring revisional surgery during long-term follow-up. As an example, in a series from California in which the mean length of follow-up was one year, 4.7 percent of patients undergoing AGB required reoperation for band revision or removal, compared with a 2.9 percent reoperation rate for patients undergoing RYGB, but the difference was not statistically significant . In a separate series of 25 adolescent patients undergoing AGB, seven (28 percent) required reoperations during a two year follow-up period, mostly for pouch dilation or tubing injuries . This reoperation rate is substantially higher than in comparable series of adolescents undergoing RYBG or SG [79,83], and the difference appears to increase over time because more of the reoperations for AGB occur during long-term follow-up. This risk of late complications is particularly relevant when considering the long-term risks and benefits of ABG in a young patient. In adult patients undergoing AGB, reoperations due to complications, including slippage, erosion, or device failure, occur in 10 to 32 percent [113,114]. (See "Late complications of bariatric surgical operations".)
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: Bariatric surgery" and "Society guideline links: Obesity in children".)
SUMMARY AND RECOMMENDATIONS — Surgical weight loss is an appropriate consideration for adolescents with severe obesity and with medical comorbidities who have failed to lose weight through conventional dietary interventions and behavioral modification.
●The most widely performed procedures in adolescents and adults are the sleeve gastrectomy (SG) and roux-en-Y gastric bypass (RYGB). Other procedures that cause significant malabsorption are generally not recommended for adolescents due to lack of safety data in this age group and concerns about long-term nutritional complications. Adjustable gastric banding (AGB) is now rarely used, due to suboptimal weight loss for many patients and increasing use of SG. (See 'Types of surgery' above.)
●In adolescents, severe obesity is defined as a body mass index (BMI) that is either ≥120 percent of the 95th percentile or ≥35 kg/m2 (whichever is lower) (figure 1A-B). This threshold corresponds to approximately the 99th percentile (Z-score 2.33). (See 'Defining severe obesity' above.)
Efficacy and complications
●Weight loss surgery has substantial clinical benefits for selected adolescents with severe obesity and medical comorbidities. This statement is based on mid-term (three year) outcomes in a large prospective cohort study, as well as retrospective studies with outcomes measured less than 10 years postoperatively. Weight loss surgery results in resolution or substantial improvement in comorbidities (figure 6), and emerging data show potential advantages of earlier surgery and good safety outcomes as compared with adults. (See 'Outcomes' above.)
●Reported weight loss for adolescents undergoing weight loss surgery ranges from 52 to 70 percent of excess body weight. In most cases, there are associated improvements in adiposity, insulin resistance, triglyceride levels, diabetes, obstructive sleep apnea, depression, and impaired quality of life. These outcomes are comparable to those reported for adults undergoing weight loss surgery. Preliminary data suggest that weight loss outcomes at three years postoperatively are comparable between SG and RYGB in adolescents (figure 5). (See 'Weight loss' above.)
●Perioperative complications in adolescents undergoing weight loss surgery are generally similar to those in adults but occur somewhat less frequently. Long-term complications are primarily nutritional and include deficiencies of iron, vitamin B12, vitamin D, and thiamine. Lifelong vitamin and mineral supplementation is imperative. However, adherence to supplementation regimens among adolescents may be poor. (See 'Outcomes' above.)
●Weight loss surgery for adolescents should be performed in the context of a multidisciplinary program with specific expertise in adolescent medicine and extensive expertise in bariatric surgery. (See 'Screening' above.)
●We suggest using a BMI of ≥35 kg/m2 as a minimum threshold for consideration of weight loss surgery in an adolescent with significant medical comorbidities (ie, those that carry a high risk of morbidity over the short-term), or a BMI of ≥40 kg/m2 for those with minor comorbidities (Grade 2C). These BMI thresholds are the same as those used for adults. Note that a BMI ≥40 represents very severe obesity in younger patients, particularly those younger than 16 years, in whom this threshold is substantially higher than the 99th percentile curve. (See 'Patient selection' above.)
●Other criteria for patient selection include lack of medically correctable causes of obesity, skeletal maturity (or near-maturity), and adequate emotional maturity and stability to ensure competent decision-making and good adherence to medical follow-up (table 1). In addition, most authorities agree that the patient should have failed organized and sustained attempts to lose weight through lifestyle intervention. (See 'Patient selection' above.)
●Perioperative and postoperative management in adolescents is similar to that for adults undergoing weight loss surgery. Diet recommendations vary depending on the type of procedure and vary slightly among centers. (See 'Perioperative safety' above and 'Diet' above.)
●For all patients who have undergone RYGB and SG, we suggest treatment with a daily multivitamin, with additional supplements of calcium, vitamin B12, and vitamin D (table 2) (Grade 2B). We perform laboratory monitoring for micronutrient deficiencies at least once annually thereafter. (See 'Nutritional supplements' above and 'Nutritional monitoring' above.)
●We recommend avoidance of pregnancy for 12 to 18 months after surgical weight loss procedures (Grade 2B). Because adolescent females appear to be at high risk for pregnancy after RYGB surgery as compared with others in their age group, all females should have counseling about pregnancy avoidance and assurance of adequate contraception as part of the preparation and follow-up after weight loss surgery. (See 'Pregnancy prevention' above.)
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