The most recent analysis from the MSBase Study Group has examined how treatment decision-making affects the risk of conversion to secondary-progressive multiple sclerosis (SPMS) (Brown et al. JAMA 2019;321:175-187). The results indicate that starting with a higher-efficacy disease-modifying therapy (DMT) or switching earlier can substantially reduce the risk of SPMS.
The propensity score-matched cohort study included data from 1555 patients (mean age 35 years at baseline) treated at 68 neurology centres in the period 1988-2017. All patients had a minimum of four years of follow-up. Starting treatment with a front-line DMT (glatiramer acetate or beta-interferon) was associated with a 29% lower risk of conversion to SPMS compared to remaining untreated. The 5-year absolute risk of SPMS was 12% in treated versus 27% in untreated patients (median follow-up 7.6 years). There was also a benefit if a front-line therapy was initiated within five years of disease onset compared to later (hazard ratio 0.77); the absolute risk was 3% with treatment versus 6% without treatment over a median follow-up of 13.4 years.