Decreased Serum/Plasma Vitamin D levels in SLE Patients: A Meta-Analysis

The evidence regarding the association between serum/plasma vitamin D (VitD) concentrations and systemic lupus erythematosus (SLE) is inconsistent. The study was based on relevant results from literatures that were identified and evaluated. The aim of this meta-analysis is to determine circulating VitD in SLE patients and explore influencing factors.

Studies examining VitD levels in SLE patients were identified through targeted searches in the PubMed and EMBASE databases (up to December 2017). Data extracted from eligible studies was synthesized to calculate the standardized mean difference (SMD), odds ratio (OR), and 95% confidence interval (CI). A fixed or a random effects model was applied to calculate the pooled SMDs and ORs depending on heterogeneity across studies.

A total of 24 studies, including 6017 patients and 18,417 controls were included. The pooled analysis suggested that VitD levels were significantly lower in SLE patients compared with those in controls [SMD= -0.09, 95%CI= -0.12 to -0.06, P < 0.001]. When the studies were stratified by ethnicity, VitD concentrations were also significantly lower in Asian, Caucasian and African patients. When the studies were stratified by age, gender, VitD level was lower in patients than that in controls. Subgroup analyses stratified by measurement type (expect for radioimmunoassay) also demonstrated consistent results. Moreover, VitD insufficiency was more prevalent in SLE patients than healthy controls [OR=6.57, 95%CI=4.64-9.29].

Compared with healthy controls, SLE patients had lower concentration of VitD. Additionally, the prevalence of VitD insufficiency is more common in SLE patients.