An Intervention Trial of Vitamin D in Clinically Isolated Syndrome

Low serum vitamin D has been associated with multiple sclerosis (MS) risk (NEJM JW Neurol Sep 13 2017 and Neurology 2017; 89:1578). PrevANZ was a phase 2, double-blind, placebo-controlled, randomized study of vitamin D₃ at doses of 1000, 5000, or 10,000 IU daily compared with placebo in patients with clinically isolated syndrome, which often progresses to MS.

Of 199 patients with clinically isolated syndrome randomized and followed for up to 48 weeks, 182 completed the study. Among the 199 participants, no benefit was observed on risk for conversion to MS across the three different doses, compared with placebo. Adjustments for age, latitude, smoking, skin color, body-mass index, enrollment season, disability, and use of glucocorticoids did n…