Vitamin D implicated in systemic lupus erythematosus

Patients with systemic lupus erythematosus (SLE) with low levels of vitamin D tend to have a more severe form of the disease, according to a systematic review and meta-analysis.

Researchers searched multiple online databases for case–control studies in which vitamin D was examined in relation to disease activity indices, C3, C4, and anti-dsDNA antibody levels in SLE patients vs healthy controls.

The Newcastle-Ottawa Scale Study was used to evaluate study quality, and Egger's test and Begg's funnel plot were applied to assess publication bias.

A total of 43 studies, which involved 2,940 SLE patients and 2,458 healthy controls, were included in the meta-analysis. Pooled data showed significantly lower vitamin D levels in SLE patients than controls, with a mean difference of −10.070 ng/mL (95 percent CI, −12.85 to −7.28; p<0.001).

Low vitamin D levels were significantly associated with higher SLEDAI scores (correlation, −0.427, 95 percent CI, −0.541 to −0.298; p<0.001) and increased anti-dsDNA antibodies (correlation, −0.397, 95 percent CI, −0.611 to −0.130; p=0.004).

Furthermore, vitamin D was positively correlated with complement components C3 (correlation, 0.268, 95 percent CI, 0.077–0.440; p=0.006) and C4 (correlation, 0.299, 95 percent CI, 0.192–0.400; p<0.001).

Similar findings were obtained in sensitivity analyses.

The meta-analysis was limited by some inconsistency and small-study biases, among others.