Confirmed disability progression provides limited predictive information regarding future disease progression in multiple sclerosis

BACKGROUND: Although confirmed disability progression (CDP) is a common outcome in multiple sclerosis (MS) clinical trials, its predictive value for long-term outcomes is uncertain. OBJECTIVE: To investigate whether CDP at month 24 predicts subsequent disability accumulation in MS. METHODS: The Comprehensive Longitudinal Investigation of Multiple Sclerosis at Brigham and Women’s Hospital includes participants with relapsing-remitting MS or clinically isolated syndrome with Expanded Disability Status Scale (EDSS) scores ≤5 (N = 1214). CDP was assessed as a predictor of time to EDSS score 6 (EDSS 6) and to secondary progressive MS (SPMS) using a Cox proportional hazards model; adjusted models included additional clinical/participant characteristics. Models were compared using Akaike’s An Information Criterion. RESULTS: CDP was directionally associated with faster time to EDSS 6 in univariate analysis (HR = 1.61 [95% CI: 0.83, 3.13]). After adjusting for month 24 EDSS, CDP was directionally associated with slower time to EDSS 6 (adjusted HR = 0.65 [0.32, 1.28]). Models including CDP had worse fit statistics than those using EDSS scores without CDP. When models included clinical and magnetic resonance imaging measures, T2 lesion volume improved fit statistics. Results were similar for time to SPMS. CONCLUSIONS: CDP was less predictive of time to subsequent events than other MS clinical features.