CHARACTERISTICS OF THE LOW ARTH PHENOTYPE IN PATIENTS WITH OSA

Abstract Introduction Obstructive sleep apnea (OSA) is a heterogenous disease with both anatomic and nonanatomic factors contributing to the pathophysiology. Recently low arousal threshold (ArTH) has been described in some patients with sleep apnea and there is early evidence emerging that it could be a clinical phenotype. The aim of this study was to characterize this phenotype in a large cohort of patients with sleep apnea confirmed by overnight polysomnography Methods The setting was a community sleep center. We performed a retrospective review of patient charts. We included patients who underwent full-night diagnostic PSG. OSA was defined as an apnea hypopnea index (AHI) of > 5. Epworth score, body mass index (BMI), neck circumference, and upper airway size using Modified Friedman (MF) were recorded. Low ArTH was calculated using AHI, fraction of hypopneas and O2 nadir.Abnormal airway narrowing was defined by MF >2. Large neck was defined by neck circumference ≥ 17 inches in males or ≥ 16 in females. Obesity was defined by BMI>30 kg/m2. Results 652 patients were included - 421(65%) were male, and 230 (35%) female. 299 (46%) of patients had a low ArTH phenotype. Mean age was similar in both groups 54 +/- 14 vs 55 +/- 13 years. Male % was less pronounced in the low ArTH group (57% of patients with low ArTH male vs 71% of without low ArTH; p<0.05). Patients with a low ArTH had lower percentage of abnormal airway narrowing (53.5 vs 62.6%, p<0.001), large neck circumference ( 64.6 vs 78.8%, p<0.001) and obesity (65.6 vs 77.9%, p<0.001). Average BMI was lower in the low ArTH group (34.8 +/- 8 vs 36.9 +/- 8; p < 0.005), and neck circumference was also lower in low ArTH group (NC 16.5 +/- 1.8 vs 17.4 +/- 1.8 respectively). Epworth sleepiness scale was lower in low ArTh group (10 +/- 8 vs 11 +/- 9; p 0.007) Conclusion We describe the phenotypic characteristics of low ArTH phenotype in a large cohort of patients with OSA. Patients with low ArTH have lower BMI, lower neck circumference, and lower Modified Friedman. Further research studies should focus on whether there are differences in therapeutic responses to this phenotype, and what clinical characteristics might help clinicians more effectively detect this phenotype. Support (If Any) NA