The PCOS Phenotype in Unselected Populations study: ethnic variation in population-based normative cut-offs for defining hirsutism.

OBJECTIVE

Hirsutism, a diagnostic feature of polycystic ovary syndrome (PCOS), is often defined using arbitrary percentile cutoffs, rather than normative cutoffs from population-based data. We aimed to define normative cutoffs for hirsutism in diverse populations.

DESIGN

Unselected population-based cluster analysis of individual participant data (IPD).

METHODS

The PCOS Phenotype in Unselected Populations (P-PUP) study IPD asset of community-based studies, underwent k-means cluster analysis, of directly assessed hirsutism, using the modified Ferriman-Gallwey (mFG) visual scale. The primary outcome was ethnicity-specific normative cutoffs for the mFG score. Medians and cutoffs were compared across ethnic groups.

RESULTS

We included 9829 unselected, medically unbiased participants, aged 18-45 years from 12 studies conducted across 8 countries including China, Iran, Italy, Nigeria, Russia, South Korea, Turkey, and the United States. The mFG cutoff scores for hirsutism on cluster analysis varied across ethnicities, ranging from 4 to 8. White Iranians had the highest cutoff score of 8, followed by White Italians and Black Africans of 7. Asian Han Chinese, White Russian, Turkish, and Black Americans shared a cutoff of 5; White Americans, Asian Koreans, Asian Russians, and Mixed Russians shared a cutoff of 4. Comparing medians and mFG cutoffs across ethnicities confirmed the same differences.

CONCLUSION

This study confirms the 2023 International PCOS Guidelines recommendations defining hirsutism as an mFG score between 4 and 6 for the majority of populations studied, with few exceptions. However, we also highlight ethnic variation in mFG cutoff scores, suggesting that clinicians consider ethnicity in optimal diagnosis and personalized interventions.