Factors associated with disability progression in multiple sclerosis

The mechanisms underlying clinical heterogeneity in multiple sclerosis (MS) are poorly understood. Evidence suggests that modifiable factors can influence relapses and disability in MS. We studied associations of several explanatory variables in relation to the progression of disability in MS. We used the time to EDSS 6 as measure of disability progression. This step, requiring a cane or support to walk a distance of 100 m, is considered to be a milestone in the progression of MS. In a cohort of women with predominantly relapsing onset MS, having children after MS onset was associated with a reduced risk to reach EDSS 6 compared to not having children after MS onset. In participants, registered by the Flemish MS society, stratifying the analysis according to relapsing onset and progressive onset MS resulted in different patterns of associations for reproductive events, sun exposure, consumption patterns and health promotion behaviour. The design of the studies does not allow to establish a causal relationship. However, the difference in assocations between relapsing onset and progressive onset MS lends support to the hypothesis that different mechanisms are underlying progression of disability.