Efficacy and safety of vitamin D supplementation in patients with systemic lupus erythematosus: A meta-analysis of randomized controlled trials

Background: The efficacy of vitamin D supplementation in patients with systemic lupus erythematosus (SLE) remains uncertain. This meta-analysis aimed to systematically evaluate the efficacy and safety of vitamin D supplementation in patients with SLE. Materials and Methods: Randomized controlled trials (RCTs) were searched in PubMed, Embase, Cochrane CENTRAL and Web of Science databases. The retrieved studies were subjected to meta-analysis using the fixed-effect or random-effect model. Results: Five eligible RCTs enrolling 490 participants were included. Compared to the placebo treatment, vitamin D supplementation significantly increased the level of serum 25-hydroxyvitamin D (25(OH) D) (5 trials, 490 participants: standard mean difference (SMD) = 2.072, 95% CI: 1.078-3.066, P < 0.001). The pooled result from 2 RCTs showed that vitamin D supplementation decreased the fatigue severity scale scores in patients with SLE (2 trials, 79 participants: SMD = -1.179, 95% CI: -1.897 to -0.460, P = 0.001). The SLE disease activity index scores and positivity of anti-double-stranded DNA antibodies (anti-dsDNA) did not differ significantly (4 trials, 223 participants: SMD = -0.507, 95% CI: -1.055-0.041, P = 0.070; 3 trials, 361 participants: Risk ratio = 0.880, 95% CI: 0.734-1.054, P = 0.165) between the vitamin D supplementation group and the placebo treatment group. None of the included studies reported severe adverse events associated with vitamin D supplementation. Conclusions: This meta-analysis suggested that vitamin D supplementation is effective in increasing the serum 25(OH) D levels, may improve fatigue, and is well-tolerated in patients with SLE, however, it does not seem to have significant effects in decreasing the positivity of anti-dsDNA and disease activity.