0562 Differences in Upper Airway Soft Tissue Volumes Between African American and Caucasian Patients with Obstructive Sleep Apnea Using Magnetic Resonance Imaging

Abstract

Introduction Research suggests greater obstructive sleep apnea (OSA) severity in African-Americans than Caucasians. However, the underlying mechanisms causing this ethnic disparity are unknown. To evaluate possible mechanisms, we compared the size of the tongue between African American and Caucasian OSA patients using magnetic resonance imaging (MRI), controlling for age, body mass index (BMI) and apnea-hypoxia index (AHI). Given prior evidence of more severe OSA in African Americans, we hypothesized these patients would have larger soft tissue volumes compared to Caucasians. Methods Upper airway soft tissue volumes, (total tongue, tongue fat, lateral walls, pterygoids, total soft tissue) were quantified using MRI and compared between Caucasian (n=133) and African American (n=175) patients with moderate OSA. Analyses were conducted using regression models controlling for age, sex, BMI and AHI. Results Among all OSA patients, African Americans had higher BMI than Caucasians (40.0±8.6 vs. 37.1±8.1 kg/m2, p=0.0024) and a higher proportion of females (66.3% vs. 36.1%; p<0.0001). There were no significant differences in age (p=0.143) or AHI (p=0.314). Controlling for these covariates, there were no differences between African American and Caucasian OSA patients in tongue fat volume (mean [95% confidence interval] difference = 479 [-3156, 4115] mm3; p=0.794). However, African Americans had a 13,286 (6,439, 20,132) mm3 larger total tongue volume compared to Caucasians (p=0.0002). Larger volumes in African Americans were also observed for the soft palate (p<0.0001), retropalatal lateral walls (p=0.003), pterygoid (p=0.034) and total soft tissue volume (p=0.0003). Conclusion African Americans were observed to have larger volumes of the tongue, soft palate, retropalatal lateral walls, pterygoids and total soft tissue volume compared to Caucasians, although there were no differences in AHI and tongue fat volume. The study contributes to the overall understanding of ethnic-specific pathology of OSA and can potentially influence how African Americans and Caucasians are diagnosed and treated specifically for the disease. Support