Association of Fat Mass and Skeletal Muscle Mass with Cardiometabolic Risk Varied in Distinct PCOS Subtypes: A Propensity Score-Matched Case-Control Study

(1) Background: polycystic ovarian syndrome (PCOS) is a heterogeneous syndrome with a constellation of cardiometabolic risk factors. We aimed to investigate if the association of body fat mass (BFM) and skeletal muscle mass (SMM) with cardiometabolic risk differed in PCOS subtypes. (2) Methods: 401 participants (245 PCOS and 156 controls) were assessed for anthropometric measurements, glucose-lipid profiles, reproductive hormones and body composition with propensity score-matched (PSM) analysis. The association of the cardiometabolic risk score (z score, calculated based on levels of obesity and gluco-lipid measurements) with BFM (estimated by trunk BFM/Height(2)) and SMM (estimated by SMM/Height(2)) was calculated. (3) Results: Trunk BFM/Height(2) and SMM/Height(2) were both positively associated with cardiometabolic risk in PCOS (trunk BFM/Height(2), OR 2.33, 95% CI 1.49-3.65; SMM/Height(2), OR 2.05, 95% CI 1.12-3.76). SMM/Height(2) associated with increased cardiometabolic risk in obese PCOS (BMI >= 28 kg/m(2), OR 2.27, 95% CI 1.15-4.47). For those with lower BMI (<28 kg/m(2)), trunk BFM/Height(2) showed a higher OR in both groups (PCOS, OR 2.12, 95% CI 1.06-4.24; control 2.04, 95% CI 1.04-4.02). Moreover, distinct associations among BMI-stratified groups were validated in hierarchical clustering identifying metabolic and reproductive clusters. (4) Conclusions: BFM and SMM are synergistically associated with higher cardiometabolic risk in PCOS women. Although BFM contributes to increased cardiometabolic risk, SMM also plays a primary role in obese PCOS. Our results highlight the importance of body composition in the management of PCOS.