The effects of daily intake of folic acid on the efficacy of methotrexate therapy in children with juvenile rheumatoid arthritis. A controlled study.

OBJECTIVE To determine the effect of 1 mg/day of folic acid on the efficacy of methotrexate (MTX) to control disease activity in children with juvenile rheumatoid arthritis (JRA). METHODS Randomized, double blind, placebo controlled, crossover trial of 13 weeks' duration. Nineteen children with the diagnosis of JRA, fulfilling the American College of Rheumatology diagnostic criteria, who had been receiving MTX for at least 6 months and whose disease status had remained stable for at least one month before entry were enrolled in the study. Subjects were randomly assigned to receive 1 mg/day of liquid folic acid or a liquid placebo for 6 weeks, followed by a one week washout period, and subsequent crossover to the alternate form for another 6 weeks. Disease activity indicators, including swollen joint count, duration of morning stiffness, physician and patient global assessment, and C-reactive protein, were assessed at study entry and at 6 and 13 weeks. RESULTS One patient flared during the first 2 weeks while taking placebo, requiring study withdrawal and exclusion from outcome analysis. For the remaining 18 patients, there was no statistical difference in disease activity indicators with folic acid treatment compared to placebo. CONCLUSION Supplementation with 1 mg/day of folic acid may not affect the clinical efficacy of oral weekly MTX in children with JRA.