Circulating Interleukin-18 Level in Systemic Lupus Erythematosus

Objective. This study aimed to evaluate the relationship between circulating interleukin (IL)-18 levels and systemic lupus erythematosus (SLE) and establish a correlation between plasma/serum IL-18 levels and SLE activity. Methods. We performed a meta-analysis comparing plasma/serum IL-18 levels in patients with SLE to controls by using fixed or random effects model based on the heterogeneity. Results. Sixteen studies with 659 SLE patients and 502 controls were included in this meta-analysis. Meta-analysis showed that IL-18 levels were significantly higher in the SLE group (standardized mean difference=1.556, 95% confidence interval=1.087 similar to 2.024, p<0.001). Stratifying by ethnicity showed that IL-18 levels were significantly elevated in the SLE groups of European, Asian, and Arab populations. Stratification by adjustment for age and/or sex revealed a significantly higher IL-18 level in the SLE group, independently of the adjustment. Subgroup analysis by sample size showed significantly higher IL-18 levels in the SLE group for both large sample (n=50) and small sample (n<50) subgroups. Subgroup analysis by data type showed significantly higher IL-18 levels in the SLE group for both original and calculated data populations. Conclusion. This meta-analysis demonstrated that circulating IL-18 levels are higher in patients with SLE.