Obstructive sleep apnea in patients with severe asthma: Prevalence and association between severity and asthma control

INTRODUCTION: Asthma and obstructive sleep apnea (OSA) are common respiratory disorders that can coexist and cause sleep disturbances. The strength of this association and the impact of OSA on asthma severity and control remain unclear. The study aims to estimate the prevalence of OSA in patients with severe asthma in Oman and to examine whether the severity of OSA contributed to the level of asthma control. METHODS: Adult patients with confirmed diagnosis of severe asthma who attended the respiratory clinic in a tertiary hospital in Oman over a period of 19 months were enrolled in the study. Eligible participants were screened by asthma control test (ACT) and Berlin questionnaire (BQ). Patients with high risk for OSA were subjected further to level 3 sleep study. The prevalence of OSA in patients with severe asthma and the associations between the severity of OSA and asthma control were calculated. RESULTS: We identified 312 adult asthma patients on Global Initiative for Asthma step 4 or 5 management out of 550 who were screened. The mean age of the study population was 56.59 +/- 12.40 years and the mean body mass index (BMI) 40.30 +/- 12.24 kg/m(2). The prevalence of OSA in asthma patients with severe asthma was found to be 32.4%. Out of the 138 well-controlled asthma patients (ACT >= 20), 35 had high risk of OSA based on BQ, and 32 were confirmed to have OSA (23%). Of the 174 uncontrolled patients, 80 patients had high risk of OSA and 69 patients were confirmed to have OSA (39.65%). Severe OSA was seen in 63.8% and 9.4% in uncontrolled and controlled asthma patients, respectively (P = 0.002). The median respiratory event index in the uncontrolled group was 43, and it was significantly higher than 12.5 in the controlled group (P < 0.001). CONCLUSIONS: The prevalence of OSA was high (32.37%) in patients with severe asthma. Uncontrolled severe asthma was significantly associated with severe OSA.