Vitamin D reduces anti-dsDNA positivity in systemic lupus erythematosus
A meta-analysis of three studies (intervention group, n=233; placebo, n=128) that evaluated the positivity to anti-dsDNA in SLE showed that vitamin D supplementation resulted in a significant drop in anti-dsDNA positivity (risk difference, -0.10; 95 percent CI, -0.18 to -0.03; p=0.005).
After 6 months of vitamin D supplementation, the following fatigue measurements in SLE showed significant improvements: fatigue interfering with social life (p=0.01), fatigue considered a problem (p=0.03), fatigue from medium effort (p=0.02), fatigue easily (p=0.003) and fatigue when performing exercise (p=0.03).
On the other hand, in rheumatoid arthritis (RA), vitamin D did not have significant effects on the visual analogue scale (VAS; mean difference, 2.79; -1.87 to 7.44; p=0.24) or on the disease activity score 28 (DAS-28; mean difference, -0.31; -0.86 to 0.25; p=0.28), according to an analysis of two studies (intervention, n=61; placebo, n=59).
Two other studies (intervention, n=124; placebo, n=128) showed that RA recurrence decreased although insignificantly (mean difference, -0.10; -0.21 to 0.00; p=0.05).
The meta-analysis included seven randomized controlled trials that investigated the effects of vitamin D supplementation on adult participants with immune-mediated rheumatic diseases. Those with exclusively bone metabolism or cardiovascular endpoints were excluded.
The databases of Medline, Embase, Lilacs, CINAHL and Cochrane were accessed for this meta-analysis.
Quality of the studies was measured from the following criteria: query of the study, randomization, blinding, concealment, participant attrition, homogeneity, outcome measures and intention-to-treat analysis. All studies had a high risk of bias for at least one of the aforementioned criteria.