Associations of Three Well-Characterized Polymorphisms in the IL-6 and IL-10 Genes with Pneumonia: A Meta-Analysis

Published data on the associations between three well-characterized polymorphisms in the interleukin 6 and 10 (IL-6 and IL-10) genes and the risk of pneumonia are inconclusive. A meta-analysis was performed to derive a more precise estimate. The electronic databases MEDLINE (Ovid) and PubMed were searched from the earliest possible year to May 2014. A total of 9 articles met the criteria, and these included 3460 patients with pneumonia and 3037 controls. The data were analyzed with RevMan software, and risk estimates are expressed as odds ratios (ORs) and 95% confidence intervals (95% CIs). Analyses of the full data set failed to identify any significant association of pneumonia risk with the IL-6 gene -174C allele (OR = 1.00; 95% CI: 0.98-1.03), the IL-10 gene -592C allele (OR = 1.20; 95% CI: 0.95-1.52), or the IL-10 gene -1082A allele (OR = 1.21; 95% CI: 0.99-1.49). In a subgroup analysis by pneumonia type, ethnicity, sample size and quality score, no significantly increased risk of pneumonia was found for individuals carrying the IL-6 gene -174C allele. There was a low probability of publication bias, as reflected by the fail-safe number. This meta-analysis suggests that there is no significantly increased risk of pneumonia associated with previously reported IL-6 and IL-10 polymorphisms.