IL18 and rheumatoid arthritis: With weak evidence, the results suggested that IL-18 -607 A/C gene polymorphisms were associated with a reduced risk of RA susceptibility using the allele model (OR = 0.76, 95% CI: 0.61 − 0.93,p=0.01), dominant model (OR = 0.67, 95% CI: 0.50 − 0.90, p=0.008), homozygote model (OR = 0.57, 95% CI: 0.35 − 0.91, p=0.02), and heterozygote model (OR = 0.71, 95% CI: 0.54 − 0.93, p=0.01) (Supplementary 2, Table 2).