Circulating irisin in patients with polycystic ovary syndrome: a meta-analysis

There is growing interest in exploring circulating (plasma/serum) irisin in polycystic ovary syndrome (PCOS) patients. This meta-analysis aimed to summarize the evidence assessing circulating irisin changes in this population. A systematic search was conducted in three databases: PubMed, Cochrane Library and Web of Science, for studies reporting irisin in PCOS patients compared with healthy controls or stratified by body mass index (BMI), or assessing irisin response to hyperinsulinemia. Effect sizes (Cohen's d with 95% confidence intervals [CI]) were calculated using random-effects models. Eight studies with 918 PCOS patients and 528 healthy controls were included. Results showed that circulating irisin was higher in PCOS patients than in overall healthy controls (d = 0.37, 95% CI 0.05 to 0.70), but not compared with BMI-matched or age- and BMI-matched controls. Circulating irisin was higher in PCOS patients with higher BMI than lower (d = 0.36, 95% CI 0.16 to 0.56). Circulating irisin decreased 2 h later in response to euglycemic hyperinsulinemia in PCOS patients with a larger magnitude than healthy controls (d = −0.32, 95% CI −0.53 to −0.11). In summary, with adjustment for BMI, circulating irisin in PCOS patients seems comparable to healthy controls, but its response to hyperinsulinemia might be impaired.