Elevated relapse rates in pediatric compared to adult MS persist for at least 6 years

Abstract Objective To compare relapse rates in pediatric-onset multiple sclerosis (POMS) and adult-onset multiple sclerosis (AOMS) over the first 6-years of disease. Methods Patients with relapsing-remitting disease onset were identified from the Partners Pediatric MS Center, Massachusetts General Hospital and Partners MS Center, Brigham and Women's Hospital. 84 POMS and 258 AOMS patients were included. Annualized relapse rates (ARR) for each individual year from year 1 to year 6, after first attack were compared using Poisson regression, as was expanded disability status scale (EDSS) score at the visit closest to each year interval. Results ARR was significantly higher in POMS compared to AOMS at individual years (except year 4), and was not significantly affected by adjustment for gender, race and proportion of time on treatment. Despite a 2.30 times higher relapse rate over 6-years, EDSS between groups did not differ. ARR in years 1–5 did not impact year 5 disability measured by EDSS in POMS. Conclusions Our findings demonstrate that higher ARR in POMS relative to AOMS is sustained over 6-years, suggesting a more inflammatory nature and potential disconnect between relapses and disability measured by EDSS early in POMS. This data may be useful when designing clinical trials for POMS.