No association between IL-1RN VNTR and the risk of duodenal ulcer: a meta-analysis

The aim of this study was to perform a meta-analysis to investigate a more authentic association between interleukin-1 RN variable number of tandem repeats (IL-1RN VNTR) and duodenal ulcer (DU). Systematic searches of electronic databases Embase, PubMed and Web of Science were performed. Statistical analyses were conducted using software Stata 11.0. The pooled odds ratios (ORs) with 95% confidence intervals (95% CIs) were applied. Publication bias was tested by Begg's funnel plot and Egger's regression test. A total of 16 studies including 2115 cases and 3622 controls were included in our final meta-analysis. There was no evidence of significant association between IL-1RN VNTR and DU (allelic model: OR = 1.04, 95% CI = 0.87-1.26; additive model: OR = 0.85, 95% CI = 0.62-1.16; dominant model: OR = 1.06, 95% CI = 0.92-1.23; and recessive model: OR = 0.83, 95% CI = 0.61-1.12). Significant protective associations were found in additive model (OR = 0.51, 95% CI = 0.31-0.83) and recessive model (OR = 0.45, 95% CI = 0.28-0.73) in Caucasian subgroup. In conclusion, our meta-analysis suggests that there is no evidence of significant association between IL-1RN VNTR and DU with or without Helicobacter pylori infection in overall population, whereas significant association is found by subgroup analyses which showed protective effect of IL-1RN allele 2 against DU risk in Caucasian population.