Contrasting bone profiles in PCOS are related to BMI: a systematic review and meta-analysis.

CONTEXT: Controversial results have emerged regarding whether PCOS is protective or increases the risk of bone frailty.

OBJECTIVE: This study investigated whether the PCOS condition affects bone parameters of premenopausal women. This is an update for a previous meta-analysis published in 2019.

DATA SOURCES: We searched MEDLINE and Embase.

STUDY SELECTION: Studies were considered eligible for the update if published in English between the 1st of October 2018 and the 31st of December 2023. The diagnosis of PCOS should be based on NIH criteria, the Rotterdam Consensus, AE-PCOS society criteria, or ICD codes in women over 18 years old. Only records with the Newcastle-Ottawa Scale > 6 were selected for data extraction.

DATA EXTRACTION: Data were extracted by two independent reviewers.

DATA SYNTHESIS: We identified 31 studies that met the inclusion criteria for qualitative analysis from 3322 studies in the whole period (1990-2023). Overall, cross-sectional studies included 1822 individuals with PCOS and 1374 controls, while cohort studies incorporated 30305 women with PCOS and 101907 controls. Contrasting profiles emerged after stratification using a BMI cutoff of 27 kg/m2. Individuals with PCOS and a BMI <27 kg/m2 exhibited lower vertebral and non-vertebral bone density, reduced bone turnover marker (osteocalcin), and increased bone resorption marker (CTX) levels. Conversely, individuals with PCOS and a BMI >27 kg/m2 exhibited increased vertebral and non-vertebral BMD, with no significant changes in bone formation and resorption markers (except osteocalcin).

CONCLUSIONS: The findings of this study alert for a low bone mass, low bone formation, and increased bone resorption PCOS with a BMI <27 kg/m2.