Prevalence of obstructive sleep apnea in patients with difficult-to-treat asthma

Background: Obstructive sleep apnea (OSA) is seen commonly in asthmatics and complicate the management of asthma. Objective: To evaluate the prevalence of OSA in a difficult-to-treat asthma (DTA) population. Methods: Asthma can not be controlled with high-dose inhaled corticosteroids with a combination of long-acting β2 agonist or another controller medications was defined as DTA. All participants underwent full-night polysomnography. Patients were categorized according to apnea-hypopnea index (AHI). Patients were considered as mild OSA with an AHI=5-15 and as moderate-severe OSA withan AHI≥15. Demographics and characteristics of asthma such as age at the diagnosis, duration of asthma, smoking and atopy status, pulmonary function tests, number of controller medications used, hospitalization and emergency room visit due to asthma, and analgesic hypersensitivity was compared according to presence of OSA. Results: We analyzed 47 (M:9/F:38) DTA patients with the mean age of 48.74±9.45 years. The mean duration of asthma was 9.17±6.5 years. 51.1% patients were atopic, 27.7% had analgesic hypersensitivity. 29.8% were former smoker. 35 patients (74%) had OSA. Sleep quality was impaired in all patients, particularly in patients with OSA. Eleven patients had mild, 24 patients had moderate-severe OSA. Presence of OSA was not statistically correlated with any characteristics of asthma, despite patients with OSA had longer duration of asthma. Conclusion: The study showed that there is remarkable high prevalence of OSA in DTA. Thus all DTA patients should be evaluated for OSA.