Association between circulating 25-hydroxyvitamin D and systemic lupus erythematosus: A systematic review and meta-analysis.

Compared with healthy controls, 25(OH)D levels are significantly lower in SLE patients, which is influenced by disease activity, ethnicity, seasons and vitamin D supplement; no matter the change of age, diseases duration and therapy of corticosteroid or immunosuppressive or neither, 25(OH)D levels are significantly decreased in SLE patients; the deficiency, insufficiency and sufficiency of vitamin D could significantly elevate, slightly decrease, and significantly decrease SLE risk, respectively; and 25(OH)D levels inversely correlate with SLEDAI.