Prevalence, associated clinical features, and impact on continuous positive airway pressure use of a low respiratory arousal threshold among male United States veterans with obstructive sleep apnea

Study Objectives: Determine the prevalence of, and clinical features associated with, a low respiratory arousal threshold (ArTH) among patients with obstructive sleep apnea (OSA), and to assess whether a low ArTH is associated with reduced long-term CPAP use. Methods: Cross-sectional and longitudinal analyses were performed in an observational study conducted among 940 male Veterans with OSA. Data for clinical characteristics, polysomnography characteristics, and long-term (5 ± 2 years) CPAP use were obtained from clinical records. Logistic regression was used to assess the associations between low ArTH and clinical features, including regular CPAP use. Results: A low ArTH was observed in 38% of participants overall, and was more common among nonobese (body mass index < 30 kg/m²) patients (55%). In adjusted analyses, increasing body mass index (per 5 kg/m²) and antihypertensive medication use were negatively associated with low ArTH, with odds ratio (OR) (95% confdence interval [CI]) of 0.77 (0.69, 0.87) and 0.69 (0.49, 0.98), respectively. Conversely, increasing age (per 10 years) and antidepressant use-OR (95% CI) 1.15 (1.01,1.31) and 1.54 (1.14,1.98), respectively-were positively associated with low ArTH. Nonobese patients with low ArTH were less likely to be regular CPAP users-OR (95% CI) 0.38 (0.20, 0.72)-in an adjusted model. Conclusions: Low ArTH is a common trait among Veterans with OSA and is more frequent among those who are older and nonobese and those taking antidepressants, but is less frequent among patients taking antihypertensive medications. A marked reduction of long-term CPAP use in nonobese patients with low ArTH highlights the importance of understanding a patient's physiologic phenotype for OSA management, and suggests potential targets to improve CPAP adherence.