Effects of simvastatin on serum adiponectin: a meta-analysis of randomized controlled trials

BACKGROUND: Effects of simvastatin on serum level of adiponectin, a protein conferring benefits in both cardiovascular and metabolic system, are not fully determined. METHODS: A meta-analysis of randomized controlled trials (RCTs) was performed. Studies were identified by searching of Pubmed, Embase, and the Cochrane Library databases. Heterogeneity among the RCTs was determined by Cochrane’s Q test and I(2) statistics. Meta-analysis was performed with random-effect model or fixed-effect model according to the heterogeneity. Meta-regression and subgroup analyses were performed to analyze the source of heterogeneity. RESULTS: Twelve RCTs with 16 comparisons and 1042 patients were included. Overall, serum adiponectin was not significantly affected by simvastatin (WMD: 0.42 μg/mL; 95% CI, -0.66–1.50 μg/mL). However, significant heterogeneity was detected (Cochrane’s Q test: p < 0.01; I(2) = 83%). Subsequent meta-regression analyses indicated that treatment duration was a significant determinant of the effects of simvastatin treatment on serum adiponectin (Coefficient 0.04, p = 0.03). Subgroup analyses demonstrated that simvastatin treatment was associated with increased adiponectin in studies with treatment duration of 12 weeks (WMD: 3.65 μg/mL; p < 0.01), but not in studies with treatment duration of ≤ 8 weeks (WMD: -0.20 μg/mL; p = 0.38). The different between the two stratums was significant (p < 0.01). CONCLUSIONS: Treatment with simvastatin of 12 weeks may increase the serum level adiponectin in patients at risk for cardiovascular diseases, but not for the short term treatment of ≤ 8 weeks.