OBJECTIVE

To compare the prevalence of polycystic ovary syndrome (PCOS) phenotypes and obesity among patients detected in referral versus unselected populations.

DESIGN

Systematic review and meta-analysis.

SETTING

Not applicable.

PATIENT(S): Thirteen thousand seven hundred ninety-six reproductive-age patients with PCOS, as defined by the extended Rotterdam 2003 criteria.

INTERVENTION(S): Review of PUBMED, EMBASE, and Cochrane Library, 2003-2016. Only observational studies were included. Data were extracted using a web-based, piloted form and combined for meta-analysis.

MAIN OUTCOME MEASURE(S): PCOS phenotypes were classified as follows: phenotype A, clinical and/or biochemical hyperandrogenism (HA) + oligo-/anovulation (OA) + polycystic ovarian morphology (PCOM); phenotype B, HA+OA; phenotype C, HA+PCOM; and phenotype D, OA+PCOM.

RESULT(S): Forty-one eligible studies, reporting on 43 populations, were identified. Pooled estimates of detected PCOS phenotype prevalence were consequently documented in referral versus unselected populations, as [1] phenotype A, 50% (95% confidence interval [CI], 46%-54%) versus 19% (95% CI, 13%-27%); [2] phenotype B, 13% (95% CI, 11%-17%) versus 25% (95% CI, 15%-37%); [3] phenotype C, 14% (95% CI, 12%-16%) versus 34% (95% CI, 25-46%); and [4] phenotype D, 17% (95% CI, 13%-22%) versus 19% (95% CI, 14%-25%). Differences between referral and unselected populations were statistically significant for phenotypes A, B, and C. Referral PCOS subjects had a greater mean body mass index (BMI) than local controls, a difference that was not apparent in unselected PCOS.

CONCLUSION(S): The prevalence of more complete phenotypes in PCOS and mean BMI were higher in subjects identified in referral versus unselected populations, suggesting the presence of significant referral bias.