The effects of statin use on inflammatory markers among patients with metabolic syndrome and related disorders: A systematic review and meta-analysis of randomized controlled trials

Current evidence suggests that statin use decreases the incidence of cardiovascular diseases (CVD) through reducing LDL cholesterol and decreasing inflammation. Metabolic syndrome (MetS) is usually associated with increased inflammatory markers and increased risk of CVD. We conducted a systematic review and meta-analysis to determine the effect of statin use on inflammatory markers including C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and interleukin-1 (IL-1) among patients with MetS and related disorders. PubMed, EMBASE, Web of Science databases, and Cochrane Library were searched for randomized controlled trials (RCTs) through April 2018. Three independent investigators evaluated study eligibilities, extracted data, and assessed study quality using the Cochrane Collaboration risk of bias tool and Jadad's quality scales. Heterogeneity was determined using Cochran's Q statistic and I-square (I-2) test. Based on the heterogeneity results, we pooled data using random-effect or fixed effect models presented as standardized mean differences (SMD) and corresponding 95% confidence intervals (CI). One hundred thirteen RCTs (19,644 patients) were included in our meta-analysis. The pooled results using random effects model showed that statin use statistically significantly decreased CRP level (SMD= -0.97; 95% CI, -1.10, -0.85; P < 0.001; I-2: 95.1%), TNF-alpha (SMD= -1.88; 95% CI, -2.40, -1.38; P < 0.001; I-2: 97.2%), IL-6 (SMD= -1.67; 95% CI, -1.98, -1.34; P < 0.001; I-2: 96.5%), and IL-1 concentrations (SMD= -8.35; 95% CI, -10.49, -6.22; P < 0.001; I-2: 98.4%) among patients with MetS and related disorders. Our meta-analysis showed beneficial effects of statin use on reducing inflammatory markers in patients with MetS and related disorders.