Association between Vitamin D level and/or deficiency, and systemic lupus erythematosus: a meta-analysis

Abstract

This study aimed to evaluate the relationship between the level of 25-hydroxyvitamin D [25(OH)D] and systemic lupus erythematosus (SLE). We searched the PUBMED, EMBASE, and Cochrane databases and performed a meta-analysis examining the vitamin D level and/or deficiency in patients with SLE, compared with that in healthy controls. In total, 18 studies consisting of 1,083 patients with SLE and 1,273 controls were included. Vitamin D level was significantly lower in the SLE group than in the control group (standardized mean difference [SMD] = −0.938, 95% CI = −1.352 to −0.524, p = 9.0 í— 10−6). Stratification by ethnicity showed a significantly decreased vitamin D level in the SLE group in the European and Arab populations (SMD = −1.485, 95% CI = −2.427 to −0.543, p = 0.002; SMD = −1.067, 95% CI = −1.251 to −0.883, p < 1.0 í— 10−8), and an association tendency between decreased vitamin D level and SLE in the Asian population (SMD = −0.874, 95% CI = −2.073 to −0.324, p = 0.153). Subgroup analysis by sample size showed a significantly lower vitamin D level in the SLE group in small- (n ≤ 100) and large-sample (n > 100) populations (SMD = −1.008, 95% CI = −1.672 to −0.344, p = 0.003; SMD = −0.863, 95% CI = −1.444 to −0.293, p = 0.003). Meta-analysis revealed a significant association between SLE and vitamin D deficiency (RR = 2.321, 95% CI = 1.361–3.960, p = 0.002). Stratification by ethnicity showed a significant association between SLE and vitamin D deficiency in European and Arab populations (RR = 2.182, 95% CI = 1.024–4.648, p = 0.043; RR = 4.550, 95% CI = 3.471–5.965, p < 1.0 í— 10−8). Our meta-analysis demonstrates that compared with controls, patients with SLE show significantly low serum levels of vitamin D, and that a deficiency of vitamin D is associated with SLE.