Association between neutrophil-to-lymphocyte ratio and polycystic ovary syndrome: A PRISMA-compliant systematic review and meta-analysis

The neutrophil-to-lymphocyte ratio (NLR) has been suggested to be a potential biomarker for assessing the systemic inflammatory response in polycystic ovary syndrome (PCOS). This meta-analysis is aimed at evaluating whether PCOS patients present with a higher NLR and whether obesity, metabolic, and hormonal indices have effects on the states. METHODS: We performed a literature search on PubMed, Embase and Web of Science (last update: August 2, 2022). Pooled standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated by applying random-effects models. Meta-regression analyses were used to explore the sources of heterogeneity and assess the relationship between NLR and several clinical parameters. Sensitivity analysis and publication bias were also assessed. RESULTS: Thirteen studies involving 826 PCOS patients and 780 healthy controls were eligible for the present meta-analysis. Generally, NLR significantly increased in PCOS women versus healthy women (SMD = 0.81, 95% CI = 0.30–1.33, P = .002). NLR disparity was subsequently investigated in obese and non-obese cohorts. Obese PCOS women exhibited a higher NLR than obese controls (SMD = 0.56, 95% CI = 0.24–0.87, P = .001), and a similar difference was shown between non-obese PCOS and non-obese controls (SMD = 0.36, 95% CI = 0.02–0.71, P = .038). No significant NLR disparity was observed between obese versus non-obese PCOS women (SMD = 0.50, 95% CI = −0.37 to 1.38, P = .259). Meta-regression analysis revealed that NLR was significantly positively associated with fasting blood glucose (P = .006) and total cholesterol levels (P = .021), but not correlated with body mass index and other parameters in PCOS patients. Sensitivity analysis indicated that no individual study significantly affected the overall pooled result, and no publishing bias was observed. CONCLUSION: PCOS women typically present with an increased NLR. Such an increase is independent of obesity and may be associated with glycolipid metabolic disorders.