0786 Associations of Physiological Traits with Pediatric Sleep Apnea Severity: Variation by Race and Ethnicity

Abstract Introduction Adenotonsillar hypertrophy increases risk for pediatric obstructive sleep apnea (OSA), likely due to increased upper airway collapsibility. Pathophysiologic determinants for OSA (or endotypes) included greater pharyngeal collapsibility, reduced dilator muscle compensation, elevated chemoreflex loop gain, and altered arousal threshold. More severe OSA and higher prevalence of residual OSA after adenotonsillectomy in Black compared to White children suggest differences in endotypes. We aimed to determine the extent to which changes in endotypes vary with participant characteristics and may explain differences in OSA severity across groups. Methods Endotypes were estimated during REM- and NREM- sleep from baseline polysomnography in children with OSA screened for participation in the Childhood Adenotonsillectomy Trial (CHAT; N=1232; age:3-9.9(y); BMI(z):0.88±1.24 [mean±SD]; Black: 47.9%; Asian:2.1%; Female:52.8%). Race and ethnicity differences in REM- and NREM-AHI levels and endotypes were examined adjusting for age, sex, BMI(z), and time in lateral position. Multivariable regression models assessed associations of REM- and NREM-endotypes (per SD) with REM- and NREM-apnea-hypopnea index (AHI; events/h), mutually adjusted for other endotypes. Mediation analysis quantified the extent to which endotypic differences explained race differences in AHI. Results The sample had a baseline AHI:4.9±8.9; REM-AHI:10.6±19.7; NREM-AHI:3.6±7.6 (mean±SD). In sex, age and BMI-adjusted multivariable analyses, AHI was higher in Black (REM-AHI: 7.81±1.01 events/h; NREM-AHI: 1.57±0.30 events/h; β±SEM) and Asian (REM-AHI: 9.37±3.35 events/h) children compared to White children. Compared with White children, Black children had higher collapsibility (0.30±0.09; β±SEM) and higher arousal threshold (0.21±0.11) in REM, while Asian children had decreased compensation (REM: −1.06±0.22; NREM: −0.48±0.11) in REM and NREM. Sex or BMI(z) were not associated with collapsibility or compensation. Endotypic analysis, adjusted for lateral position only, showed that higher REM- and NREM-AHI were associated with greater collapsibility (REM: 13.64±1.73; NREM: 5.58±0.57; β±SEM), reduced compensation (REM: −4.22±0.98; NREM: −1.88±0.23) and higher arousal threshold (REM: 3.42±0.97; NREM: 0.72±0.17). Mediation analysis showed that the higher REM-AHI in Black children was partially explained by elevated arousal threshold (0.21 SD; percentage mediated=19 [95%CI:3-39]%). Conclusion Endotypes are associated with pediatric OSA severity, and partially explain race-associated differences in AHI. These results suggest opportunities for targeting mechanistic traits to improve the outcomes of surgical therapies for OSA. Support (if any)