0540 Varying Hypopnea Definitions and Missed Treatment Opportunities in Obstructive Sleep Apnea

Abstract Introduction The definition of hypopnea, and by extension the calculation of the apnea-hypopnea index (AHI), may vary based on insurance status, raising important ethical concerns and treatment implications. The aim of this study is to compare two definitions of hypopnea: ≥ 4% decrease in the oxygen saturation (4% criterion) vs ≥ 3% decrease in the oxygen saturation or an arousal (3% criterion) in the diagnosis, severity determination and potential missed treatment opportunities in obstructive sleep apnea (OSA). Methods A post-hoc secondary cross-sectional analysis was conducted using data from the MESA Sleep Ancillary Study cohort. The dataset was obtained from the National Sleep Research Resource (NSRR). Concordance/discordance between the two hypopnea criteria used to calculate the AHI were determined using chi square tests of independence and effect size determined using Cramér’s V. Comparisons include diagnosis and severity of OSA and potential treatment eligibility with CPAP and Tirzepatide. Subgroup analyses examined variations by age, sex and race/ethnicity. Results Among 2057 participants analyzed, the mean age was 69.6 years (SD 9.1), 53.6% were female, 36.1% White, 27.9% Black, 12.2% Asian, 23.9% Hispanic and average BMI was 28.7kg/m2. Overall, 60% were reclassified using the 4% criterion resulting in either a downgrade in severity or loss of diagnosis as compared to the 3% criterion. Among those with mild OSA using the 3% criterion (n=622), 71.1% were reclassified as no OSA; among moderate OSA (n=609), 28% were downgraded to no or mild OSA; among severe OSA (n=611), 49.8% were downgraded to a lower severity category. In addition, 61.3% of participants eligible for CPAP using the 3% criterion became ineligible using the 4% criterion (p < 0.0001, Cramér’s V = 0.63). Potential Tirzepatide eligibility decreased by 35.2% when using the 4% criterion. Discordance was significantly higher among females (65.9% vs 57.5%, p=0.0018). Conclusion The 4% criterion leads to substantial underdiagnosis and treatment misclassification, disproportionately affecting females and with discordance across all severity categories. Standardizing the hypopnea definition to the 3% criterion across all payers may improve diagnostic consistency, expand access to effective therapies, and promote health equity in OSA care. Support (if any) None