Natural history of multiple sclerosis: risk factors and prognostic indicators

To highlight progress in the description of the natural course and prognosis of multiple sclerosis.

The general evolution of multiple sclerosis is now well known at the level of patient groups. Characteristics of relapses early in the disease and the occurrence of a progressive phase seemed to be the most reliable prognostic factors. Recent works suggest that the progressive phase in multiple sclerosis could be an age-dependent, degenerative process, independent of previous relapses, and that the initial course of the disease does not substantially influence age at disability milestones. By contrast, a younger age at disease onset strongly correlates with a younger age when reaching disability landmarks, confirming that even if it takes longer for younger patients to accumulate irreversible disability, they are disabled at a younger age than patients with later onset. Multiple sclerosis might be considered as one disease with different clinical phenotypes, rather than an entity encompassing several distinct diseases.

Overall course and prognosis in multiple sclerosis is most likely to be related to age and the occurrence of the progressive phase of the disease, rather than to relapses or other clinical parameters. Individual prognosis remains hazardous.