In the pooled analysis of all eligible studies (38 studies), circulating resistin levels were significantly higher in PCOS women compared with non-PCOS controls (random effects, WMD = 1.96 ng/ml; 95% CI = 1.25 to 2.67, P ≤0.001) (Fig 2 and Table 2), with a significant heterogeneity across studies (I2 = 96.9%; p = ≤0.001). Here, RETN is linked to polycystic ovary syndrome.