Predictors of relapse and disability progression in MS patients who discontinue disease-modifying therapy

Background: Discontinuation of disease-modifying therapies (DMTs) for MS is common. MSBase, a large global observational registry, affords a unique opportunity to investigate predictors of 'post-DMT' relapses and confirmed disability progression (CDP) in a diverse group of patients exposed to different DMTs. Materials/methods: Main inclusion criteria: clinician-confirmed MS diagnosis (2010 McDonald criteria); age 18 at index DMT start; >= 12 months on index DMT prior to discontinuation; >= 24 months of follow-up post-discontinuation; did not restart DMT for >= 6 months. Predictors of time to first relapse and 3-month CDP were analyzed using Cox proportional hazards regression adjusted for age, gender, baseline EDSS, EDSS stability and relapse-free period for >= 1 year prior to discontinuation, calendar epoch, index DMT and reason for discontinuation. Results: 4842 patients (74.2% female) from 20 MSBase Centers met our inclusion criteria. 3556 (73%) discontinued one of IFN beta preparations, 849 (18%) - glatiramer acetate, 308 (6%) - natalizumab and 129 (3%) - fingolimod; other DMTs were excluded because too few records were available. Overall post-discontinuation annualized relapse rate (95% CI) was 0.224 (0.219, 0.229) and CDP rate was 8.23 (7.72, 8.76) per 100 person years. Risk of post-DMT relapse was higher in younger patients, female patients, those with moderate disability and a relapse within 1 year of discontinuation. Hazard of CDP increased with increasing disability at baseline and disease progression within 3 years prior to stopping DMT. Of all the DMTs, only natalizumab was associated with increased risk of both post-DMT relapse and CDP. Conclusions: Knowledge of post-DMT relapse and disability progression rates and predictors of post-DMT disease activity allows for a more informed discussion of DMT discontinuation in those patients who are considering this option.