Disability progression in multiple sclerosis: a Tunisian prospective cohort study

Data regarding multiple sclerosis (MS) course in North Africans are scarce and mainly retrospective. To prospectively assess disability progression of multiple sclerosis in Tunisia. Analysis was performed in 600 patients from the MS database of the Mongi Ben Hmida National Institute of Neurology (Tunis, Tunisia), prospectively recorded over a 10-year period. Two MS phases were defined: phase 1, from MS clinical onset to Disability Status Scale (DSS) 3; and phase 2, from DSS 3 to DSS 6. Median durations of both phases and median ages at DSS 3 and DSS 6 were estimated using the Kaplan-Meier method. Median ages at DSS scores 3 and 6 were 48 years (95% confidence interval (CI), 45-50) and 53 years (95% CI, 52-55), respectively. Median time from onset to DSS 3 (phase 1 duration) was 9 years (95% CI, 7-11) and median time to DSS 6 was 12 years (95% CI, 10-15). Median phase 2 duration was 3 years (95% CI, 2.4-3.6). Males and progressive-onset patients had faster disability worsening during the first phase of the disease. Conversely, disability progression during the second phase was independent of gender and MS phenotype at onset. Our study showed that disability progression followed a two-stage process in Tunisian MS patients with however a more aggressive course compared to that in Westerners.