A Serum Vitamin D Level <25nmol/L Pose High Tuberculosis Risk: A Meta-Analysis

Background Low serum Vitamin D is considered to be associated with tuberculosis while the "dangerous" level was not clear. The aim of this study was to identify the association between tuberculosis and serum Vitamin D levels via synthesis of available evidence. Methods A search of EMBASE, Medline, ISI Web of knowledge, and Pubmed was conducted. The number of subjects of tuberculosis and no-tuberculosis groups in four Vitamin D range. Meta-analyses were performed and presented by odds ratios (ORs) and corresponding 95% confidence intervals (CIs). Results A total of 15 studies involving 1440 cases and 2558 controls were included. A significantly increased risk of tuberculosis was found in two ranges: <= 12.5 nmol/L: pooled OR = 4.556, 95% CI = 2.200-9.435; 13-25 nmol/L: pooled OR = 3.797, 95% CI = 1.935-7.405. No statistically significant risk of tuberculosis was found in the range of 26-50 nmol/L (pooled OR = 1.561, 95% CI = 0.997-2.442). In range 51-75 nmol/L, no positive association was found (pooled OR = 1.160, 95% CI = 0.708-1.900). Conclusions This study found that a serum Vitamin D level <= 25 nmol/L was significantly associated with an increased risk of tuberculosis while the range of 51-75 nmol/L was not. The range 26-50nmol/L posed potential high tuberculosis risk. Future large-scale, well-designed studies are needed to verify these results.