Medline ® Abstracts for References 162-164

Multiple sclerosis can follow very different patterns of evolution and variable rates of disability accumulation. This raises the issue whether it represents one or several distinct diseases. We assessed demographic and clinical characteristics in 1844 patients with multiple sclerosis that we categorized according to the classification of Lublin and Reingold (1996) into 1066 (58%) relapsing-remitting, 496 (27%) secondary progressive, 109 (6%) progressive relapsing and 173 (9%) primary progressive cases of multiple sclerosis. Relapsing-remitting and secondary progressive cases shared similar age at disease onset (median = 28.7 versus 29.5 years; P = 0.21), initial symptoms of the relapsing-remitting phase, degree of recovery from the first neurological episode, and time from the first to the second episode. By contrast, disease duration was twice as long in secondary progressive than in relapsing-remitting cases (mean +/- SD = 17.6 +/- 9.6 versus 8.7 +/- 8.6 years; P<0.001). Progressive relapsing and primary progressive cases were essentially similar in their clinical characteristics. In patients experiencing a progressive course, median age at onset of progressive phase was similar in secondary progressive cases and in cases who were progressive from onset (39.1 versus 40.1 years; P = 0.47). The proportion of cases with superimposed relapses during progression was approximately 40% in both categories. Finally, the 1562 patients with an exacerbating-remitting initial course and the 282 patients with a progressive initial course of the disease were essentially similar with respect to the time course of disability accumulation from assignment to a given disability score, and the age at assignment of disability landmarks. These observational data suggest that the clinical phenotype and course of multiple sclerosis are age dependent. Relapsing-remitting disease can be regarded as multiple sclerosis in which insufficient time has elapsed for the conversion to secondary progression; secondary progressive forms as relapsing-remitting multiple sclerosis that has 'grown older'; and progressive from onset cases as multiple sclerosis 'amputated' from the usual preceding relapsing-remitting phase. Times to reach disability milestones, and ages at which these landmarks are reached, follow a predefined schedule not obviously influenced by relapses, whenever they may occur, or by the initial course of the disease, whatever its phenotype. This leads to a unifying concept of the disease in which primary and secondary progression might be regarded as essentially similar. From the clinical and statistical positions, multiple sclerosis might be considered as one disease with different clinical phenotypes rather than an entity encompassing several distinct diseases-the position of complexity rather than true heterogeneity.

OBJECTIVE: To identify clinical and demographic factors associated with long-term disability in patients with relapsing-remitting multiple sclerosis.

DATA SOURCES: We searched the MEDLINE (1966-May 2005), EMBASE, CINAHL, Cochrane, and PsycINFO computerized databases, and reviewed reference lists of retrieved articles.

STUDY SELECTION: We included studies that examined predictors of long-term disability in patients with relapsing-remitting multiple sclerosis. We excluded studies that did not distinguish relapsing-remitting multiple sclerosis from primary progressive multiple sclerosis, enrolled fewer than 40 subjects, observed subjects for less than 5 years, or collected follow-up information in less than 80% of the inception cohort.

DATA EXTRACTION: Two reviewers assessed study quality in 4 domains: cohort assembly, definitions and assessments of prognostic factors and outcomes, and statistical methods. One reviewer extracted data on the direction, magnitude, precision, and statistical significance of the effect of each predictor on prognosis.

DATA SYNTHESIS: Heterogeneity of study designs precluded us from pooling the results of 27 eligible studies. Study quality was limited by cross-sectional design, enrollment of prevalent cases from referral centers, and lack of multivariate adjustment. Sphincter symptoms at onset (hazard ratio, 1.1-3.1), incomplete recovery from the first attack (hazard ratio, 1.3-3.3), and a short interval between the first and second attack (hazard ratio, 1.6-1.9) were most strongly and consistently associated with poor prognosis. Other factors widely believed to be of prognostic importance, including sex and age at onset, demonstrated inconsistent or weak effects on prognosis.

CONCLUSIONS: The most robust predictors of long-term physical disability in relapsing-remitting multiple sclerosis are sphincter symptoms at onset and early disease course outcomes. These factors can be used to guide treatment decisions for drugs with significant toxicities.

Prognosis of multiple sclerosis is highly variable. Clinical variables have been identified that are assessable early in the disease and are predictors of the time from the disease onset to the onset of irreversible disability. Our objective was to determine if these clinical variables still have an effect after the first stages of disability have been reached. We determined the dates of disease onset and assignment of scores of irreversible disability in 1844 patients with multiple sclerosis. We used three scores on the Kurtzke Disability Status Scale as benchmarks of disability accumulation: 4 (limited walking but without aid); 6 (walking with unilateral aid); and 7 (wheelchair bound). We used Kaplan-Meier analyses and Cox regression models to determine the influence of the clinical variables on the time to disability onset. Median times from onset of multiple sclerosis to assignment of a score of 4, 6 and 7 were significantly influenced by gender, age, symptoms and course (relapsing-remitting or progressive) at onset of the disease, degree of recovery from the first relapse, time to a second neurological episode, and the number of relapses in the first 5 years of the disease. Similarly, times from onset of multiple sclerosis to a score of 6 and 7 were influenced by time to a score of 4. In contrast, none of the variablessubstantially affected the time from a score of 4 to a score of 6 or 7, or from a score of 6 to a score of 7. Early assessable clinical variables significantly influence the time from the onset of multiple sclerosis to the assignment of a disability score of 4, but not the subsequent progression of irreversible disability.