Introduction:
Both polycystic ovary syndrome (PCOS) and the metabolic syndrome (MS) are associated with increased long-term risk of type 2 diabetes and cardiovascular diseases in association with aetiological factors including obesity and insulin resistance. However, the prevalence of MS in PCOS varies widely and the contribution of socio-demographic or biological factors to this variability is not known.
Methods:
A literature search was conducted in MEDLINE, CINAHL, EMBASE and clinical trial registries to identify studies reporting prevalence of MS in women with or without PCOS. Data were presented as odds ratio (OR [95% confidence interval (CI)] with random-effects meta-analysis by Mantel-Haenszel methods. Subgroup analyses and meta-regression were conducted for variables including age, BMI, geographical and income regions, insulin and androgens.
Results:
A total of 4530 articles were reviewed and 34 were included for the systematic review and meta-analysis comprising 21310 women). Women with PCOS had an increased prevalence of MS (OR 2.39, 95% CI 1.81, 3.15; BMI-matched studies OR 2.45, 95% CI 1.37, 4.36). Women with PCOS in Americas (OR 4.19, 95% CI 1.30, 13.50) and English-speaking countries (OR 3.58, 95% CI 2.75, 4.66) had significantly greater risk of MS compared to other regions (P=0.01 for subgroup differences). Adolescents with PCOS (OR 4.87, 95% CI 3.17, 7.49) also had greater risk of MS than adults (OR 1.48, 95% CI 1.11, 1.96) with PCOS compared with controls (P<0.0001 for subgroup differences).
Conclusion:
Women with PCOS have increased risk of MS in both BMI-matched and non BMI-matched studies. Studies in Americas countries, English-speaking countries and adolescents reported further increased risk of MS. Further studies are required to explore the reasons for these differences.