Vitamin D supplementation and disease activity in patients with immune-mediated rheumatic diseases: A systematic review and meta-analysis

BACKGROUND: Vitamin D serum levels and the presence and activity of rheumatic conditions have been associated. However, many studies are merely observational, and the existent randomized clinical trials were never systematically analyzed. Therefore, this study aims to provide a systematic review and meta-analysis of such a topic. METHODS: MEDLINE, EMBASE, LILACS, COCHRANE, and CINAHL were explored to identify randomized trials that investigated clinical repercussions of vitamin D (or analogs) supplementation for at least 3 months in rheumatic diseases. Standardized clinical and/or laboratorial outcomes related to disease activity were analyzed according to each disease before and after supplementation. RESULTS: Database searches rendered 668 results; 9 were included—5 on rheumatoid arthritis, 3 on systemic lupus erythematosus, and 1 on systemic sclerosis. Seven of the studies were meta-analyzed. After vitamin D supplementation, rheumatoid arthritis recurrence decreased; however, not significantly (risk difference = −0.10, 95% CI = −0.21, 0.00, P = .05). No statistical significance was observed regarding visual analog scale (mean difference = 2.79, 95% CI = −1.87, 7.44, P = .24) and disease activity score28 (mean difference = −0.31, 95% CI = −0.86, 0.25, P = .28). Regarding systemic lupus erythematosus, anti-dsDNA positivity was significantly reduced (risk difference = −0.10, 95% CI = −0.18, −0.03; P = .005). CONCLUSION: Vitamin D supplementation reduced anti-dsDNA positivity on systemic lupus erythematosus and could possibly reduce rheumatoid arthritis recurrence, although novel randomized clinical trials are needed to confirm and extend the benefits of this hormone in immune-mediated rheumatic diseases.