Low circulating adiponectin levels in women with polycystic ovary syndrome: an updated meta-analysis

Adiponectin, as an important adipocytokine, plays a pivotal role in the regulation of insulin sensitivity and metabolism. It has been reported that circulating adiponectin levels were decreased in women with polycystic ovary syndrome (PCOS). However, the results remained inconsistent. In order to derive a more precise estimation of this relationship, a large meta-analysis was performed in this study. A comprehensive systematic electronic search was conducted in electronic databases PubMed, EMBASE, and Web of Science up to November 30, 2013. Pooled weighted mean differences (WMDs) with 95% confidence intervals (CIs) were calculated to estimate the strength of the association. A meta-analysis technique was used to study 38 trials involving 1,944 PCOS women and 1,654 healthy controls. Overall pooled adiponectin levels in women with PCOS were significantly reduced compared with healthy controls (WMD -2.67, 95% CI -3.22 to -2.13; P = 0.000), yet with significant heterogeneity across studies (I(2) = 95.9%, P = 0.000). In subgroup analysis by HOMA-IR ratio and total testosterone ratio, inconsistent results were presented. No single study was found to affect the overall results by sensitivity testing. Meta-regression suggested that BMI might contribute little to the heterogeneity between including studies. Cumulative meta-analysis demonstrated the reliability and stability of the meta-analysis results. No evidence of publication bias was observed. Our meta-analysis suggested that circulating adiponectin levels in women with PCOS were significantly lower than those in healthy controls, which indicated that circulating adiponectin might play a role in the development of PCOS.