Vitamin D status is associated with relapse rate in pediatric-onset multiple sclerosis

Objective: We sought to determine if vitamin D status, a risk factor for multiple sclerosis, is associated with the rate of subsequent clinical relapses in pediatric-onset multiple sclerosis. Methods: This is a retrospective study of patients with pediatric-onset multiple sclerosis or clinically isolated syndrome who were consecutively recruited into a prospective cohort at their clinical visit at the pediatric multiple sclerosis center of University of California, San Francisco or State University of New York at Stony Brook . Of 171 eligible patients, 134 (78%) with multiple sclerosis/clinically isolated syndrome were included in the cohort; a further 24 were excluded from this analysis due to lack of available serum (n = 7) or lack of follow-up (n = 17). Serum 25-hydroxyvitamin D₃ levels were measured and were adjusted to reflect a deseasonalized value. The adjusted serum 25-hydroxyvitamin D ₃ level was the primary predictor in a multivariate negative binomial regression model in which the main outcome measure was the number of subsequent relapses. Results: Among the 110 subjects, the mean unadjusted 25-hydroxyvitamin D₃ level was 22 ± 9ng/ml. After adjustment for age, gender, race, ethnicity, disease duration, disease-modifying therapy, and length of follow-up, every 10ng/ml increase in the adjusted 25-hydroxyvitamin D₃ level was associated with a 34% decrease in the rate of subsequent relapses (incidence rate ratio, 0.66; 95% confidence interval, 0.46-0.95; p = 0.024). Interpretation: Lower serum 25-hydroxyvitamin D₃ levels are associated with a substantially increased subsequent relapse rate in pediatric-onset multiple sclerosis or clinically isolated syndrome, providing rationale for a randomized controlled trial of vitamin D supplementation.