Disease course after clinically isolated syndrome in children versus adults: a prospective cohort study

Background and purpose Clinically isolated syndrome (CIS) is a first demyelinating event of the central nervous system and can be a single event. After CIS, a chronic disease course with ongoing inflammation and relapses might occur, resulting in a diagnosis of multiple sclerosis (MS). As yet, there has been no prospective exploration of whether children and adults with CIS have the same disease course. Methods Patients with CIS, whose age ranged from 1 to 50 years, were prospectively followed. We divided the patients into three different age groups, i.e. 1–10, 11–17 and 18–50 years old. Demographic data, disease course, time to MS diagnosis and annualized relapse rates (ARRs) were compared among these groups. Results We included 383 patients with CIS, of whom 218 (56.9%) were diagnosed with MS. Children of between 11 and 17 years old had the highest rate of MS conversion (83.5% vs. 50.0% in the other age groups together, P < 0.01) and the shortest time to MS diagnosis [median time 2.6 months (interquartile range, 0.6–6.0) vs. 8.2 months (interquartile range, 1.9–28.2) in the other age groups together, P < 0.01). ARRs corrected for follow‐up were higher in children of