Frailty and relapse activity in multiple sclerosis: A longitudinal observation.

Recent cross-sectional investigations suggest a relationship between frailty, as measured by Frailty Index (FI), and multiple sclerosis (MS). However, if and how frailty is associated with relapse activity in MS is still unknown. To explore this issue, a one-year follow-up study involving 471 patients was conducted. A univariate regression model showed an inverse association between baseline FI score and the presence of relapse, which was also confirmed in the multivariate model. These results suggest that frailty may reflect pathophysiological mechanisms involved in MS disease activity and that the FI may be used as an enrichment criterion in clinical trials.