Multiple sclerosis relapse risk factors across treatment eras.

Background: Age and sex were shown to influence multiple sclerosis (MS) relapse activity in the 1990s. Whether relapse risk factors are the same with new treatment paradigms is unclear. We evaluate predictors of clinical relapse following the first clinic visit (FV) across different treatment eras in a large, retrospective cohort. Methods: Adults with clinically isolated syndrome or relapsing-onset MS were divided into cohorts with FV at the Brigham Multiple Sclerosis Center (Boston, MA) from 1997 to 2010 ("early") and 2010 to 2020 ("recent"). Risk factors for relapse in 3 years after the FV were assessed for each cohort using multivariable logistic regression, and interaction terms were evaluated. Results: 2192 patients were included (early: 1536; recent: 656). Younger age, female sex, relapsing-remitting disease, more prior relapses, and the use of platform therapy were associated with a future relapse in the early cohort. Age, family history of MS, and platform therapy were predictive in the recent cohort. Interaction terms for all variables were not significant. Model accuracy was similar across treatment eras. Conclusions: Predictors of future relapse did not differ substantially across treatment eras. Younger age and the use of less effective therapies were strong risk factors at FV. However, significant heterogeneity exists in individuals' relapse risk.