0932 Impact of Body Mass Index (BMI) and Position on Obstructive Sleep Apnea (OSA) in Postmenopausal Women

Abstract Introduction Obstructive sleep apnea (OSA) is influenced by age, body mass index (BMI), and sex, with postmenopausal women showing increase in OSA. The role of BMI in postmenopausal women remains poorly understood. This study investigates how BMI affects supine AHI in postmenopausal women compared to men and premenopausal women. Methods 846 subjects ≥18 years (383, 45.3%, males and 463, 54.7%, females) with polysomnograms at the University of Iowa Hospitals and Clinics from July 2011 to June 2012, were categorized into four groups: men < 55 years (YM, n = 187), men ≥55 years (OM, n = 264), premenopausal women (YW, women < 55, n = 197), and postmenopausal women (OW, women ≥55, n = 257) and placed into BMI categories: normal (< 25 kg/m²), overweight (25–30 kg/m²), obese (30–40 kg/m²), and morbidly obese (≥40 kg/m²). Supine AHIs were analyzed across groups to assess the impact of BMI on OSA severity. Linear regression, analysis of covariance (ANCOVA), and Tukey’s HSD test were performed for analysis. Results The supine AHI values for each BMI group were: men < 55 years: 3.2, 10.1, 18.1, 21.0; men ≥55 years: 9.5, 13.9, 23.2, 29.4; premenopausal women (women < 55): 1.1, 2.9, 7.0, 12.0; and postmenopausal women (women ≥55): 13.2, 14.8, 17.3, 15.5. Using linear regression model, slopes of supine AHI value for BMI changes were as the following for each group (YM 0.65, OM 0.29, YW 0.24, OW -0.05). Multiple regression model showed much attenuated effect of BMI on supine AHI in postmenopausal women compared to all other groups (p = 0.023 compared to the reference group OM). YM group showed stronger effect of BMI on supine AHI than OM (p =0.024). Conclusion BMI’s effect on Supine AHI differs across groups with the postmenopausal women showing significantly attenuated relationship between BMI and supine AHI. This underscores the importance of considering non-BMI factors, such as age- and sex-related physiological changes in postmenopausal women to improve the effectiveness of treatments like positional therapy and CPAP. Further studies are warranted to investigate the underlying mechanisms and develop targeted interventions for postmenopausal women with OSA. Support (if any)