Risk of Persistent Disability in Patients with Pediatric-Onset Multiple Sclerosis

Importance: Availability of new disease-modifying therapies (DMTs) and changes of therapeutic paradigms have led to a general improvement of multiple sclerosis (MS) prognosis in adults. It is still unclear whether this improvement also involves patients with pediatric-onset MS (POMS), whose early management is more challenging. Objective: To evaluate changes in the prognosis of POMS over time in association with changes in therapeutic and managing standards. Design, Setting, and Participants: Retrospective, multicenter, observational study. Data were extracted and collected in May 2019 from the Italian MS Registry, a digital database including more than 59000 patients. Inclusion criteria were MS onset before age 18 years, diagnosis before January 2014, and disease duration of at least 3 years. Exclusion criteria were primary progressive MS, Expanded Disability Status Scale (EDSS) score of at least 8 one year after onset, unavailability of diagnosis date, and less than 2 EDSS score evaluations. Eligible patients were 4704 patients with POMS. According to these criteria, we enrolled 3198 patients, excluding 1506. Exposures: We compared time to reach disability milestones by epoch of MS diagnosis (<1993, 1993-1999, 2000-2006, and 2007-2013), adjusting for possible confounders linked to EDSS evaluations and clinical disease activity. We then analyzed the difference among the 4 diagnosis epochs regarding demographic characteristics, clinical disease activity at onset, and DMTs management. Main Outcomes and Measures: Disability milestones were EDSS score 4.0 and 6.0, confirmed in the following clinical evaluation and in the last available visit. Results: We enrolled 3198 patients with POMS (mean age at onset, 15.2 years; 69% female; median time to diagnosis, 3.2 years; annualized relapse rate in first 1 and 3 years, 1.3 and 0.6, respectively), with a mean (SD) follow-up of 21.8 (11.7) years. Median survival times to reach EDSS score of 4.0 and 6.0 were 31.7 and 40.5 ye