Supplementary Material for: Associations between Polymorphisms in the IL-1 Gene and the Risk of Rheumatoid Arthritis and Systemic Lupus Erythematosus: Evidence from a Meta-Analysis

Background: Previous studies on polymorphisms in interleukin-1 (IL-1) and the risk of rheumatoid arthritis (RA)/systemic lupus erythematosus (SLE) yielded inconsistent results. Objectives: The authors performed this meta-analysis to more robustly evaluate associations between polymorphisms in the IL-1 gene and the risk of RA/SLE. Methods: MEDLINE, Embase, Web of Science, Wanfang, VIP, and CNKI were systematically searched for eligible studies, and 34 relevant studies were finally selected to be eligible for inclusion. Results: We found that IL-1A +4845G/T polymorphism was significantly associated with the risk of RA in the overall population (dominant comparison: p = 0.02; overdominant comparison: p = 0.05; allele comparison: p = 0.04), whereas IL-1B +3954C/T polymorphism was significantly associated with the risk of RA in the overall population (overdominant comparison: p = 0.03; allele comparison: p = 0.01) and Asians (recessive comparison: p = 0.007; allele comparison: p = 0.002). In addition, we found that IL-1A –889C/T polymorphism was significantly associated with the risk of SLE in Caucasians (allele comparison: p = 0.04), IL-1B –31T/C polymorphism was significantly associated with the risk of SLE in the overall population (recessive comparison: p = 0.04), and IL-1B –511C/T polymorphism was significantly associated with the risk of SLE in Asians (recessive comparison: p = 0.01; allele comparison: p = 0.03). Conclusions: This meta-analysis suggests that IL-1A +4845G/T and IL-1B +3954C/T polymorphisms may influence the risk of RA, whereas IL-1A –889C/T, IL-1B –31T/C, and IL-1B –511C/T polymorphisms may influence the risk of SLE.