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

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.

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.

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 <18 years old than in adults of ≥18 years old with MS (mean ARR, 0.65 vs. 0.43, P < 0.01).

Children with CIS tend to have a more inflammatory disease course appearing from higher ARRs in all children and the highest rate of MS conversion in 11-17-year-old children. This supports early initiation of disease-modifying therapy in children, perhaps even at the first event in children at high risk for MS in line with clinical practice in adults.