Determine the prevalence and factors associated with LRAT in African American patients evaluated for OSA.

Non-anatomic physiologic traits contribute to the development of OSA. Respiratory Arousal Threshold (RAT) describes cortical arousal due to derangement in pressure and gas exchange during upper airway collapse.  LRAT causes premature termination of ventilatory drive leading to increased cortical arousals and sleep fragmentation.  African Americans (AA) have increased prevalence and severity of OSA with decreased CPAP compliance.  How much LRAT contributes to OSA pathogenesis and treatment response in AA remains unknown.

Observational cohort study of 151 (AA) patients evaluated for sleep apnea at Howard University Hospital from 2018-2019. Clinical data including age, BMI, medical history, medications, social history and polysomnography results were obtained. Group difference evaluated using Non-parametric T-test and ANOVA analysis. A scoring tool described by Bradley et al was used to estimate the RAT. A score of 1 point was assigned to each polysomnography criteria: AHI<30 events/hour of sleep, proportion of hypopnea >58.3% and a nadir SpO2>82.5%. A score ≥2 indicates LRAT.

 The cohort consisted of 95 females and 56 males. Population mean RAT score (MRAT) was 1.66 and 60.9% of patients had LRAT. Within clinical categories the following scored the highest: age 61-70 years [1.86, 95% CI (1.50, 2.22), p=0.628], BMI 18.5-24.9 [2.00, 95% CI (1.06, 2.94), p=0.027],  Females [1.99, 95% CI (1.74, 2.07) p=0.000].  AHI scores [5-15] had higher MRAT scores 95% CI (2.31, 2.72) p=0.000 and  Non-smokers had higher scores than smokers [1.78, 95% CI (1.61, 1.98) p=0.043](Mann-Whitney-UTest, mean-rank (smokers 67.73) vs (non-smokers 81.16)).