Clinical course of multiple sclerosis: A nationwide cohort study.

BACKGROUND: The course of multiple sclerosis (MS) has been studied in several cohorts; however, results have varied significantly.

OBJECTIVE: To describe the clinical course of MS in a nationwide cohort of patients.

METHOD: Data from the Swedish MS register (SMSreg) were used to estimate the median time to the sustained Expanded Disability Status Scale (EDSS) scores 3.0, 4.0 and 6.0, onset of secondary progressive multiple sclerosis (SPMS) and death using Kaplan-Meier method. A possible effect of first-line treatments on age at EDSS 6.0 and SPMS was estimated.

RESULTS: In all, 12,703 patients were included. Median ages at EDSS scores 3.0, 4.0 and 6.0 were 55.4 (95% confidence interval (CI): 54.8-55.8), 60.7 (95% CI: 60.1-61.2) and 64.3 (95% CI: 63.6-64.7), respectively. Median age at SPMS was 57.4 (95% CI: 56.9-57.9). The median age at the time of death was 80.5 (95% CI: 79.9-81.1). Males and progressive-onset patients showed higher risks of disability worsening. On average, treated patients gained 1.6 years (95% CI: 0.2-3) to EDSS 6.0 as a result of treatment.

CONCLUSION: Ages at disability milestones in this population-based cohort were higher than previously described in clinic- and regional-based samples. Nevertheless, MS patients die at younger age and live at an average almost 20 years with moderate and 30 years with severe disability.