Associations between obstructive lung disease and symptoms of obstructive sleep apnoea in a general population

Objectives To examine the prevalence of self-reported symptoms of obstructive sleep apnoea (OSA) in relation to asthma, respiratory symptoms and pulmonary function. A secondary objective was to determine how sex impacted these relationships. Methods A random sample of all adults aged 47-48 and 71-73 years living in Bergen, Norway, were invited. Participants (3506, 69%) underwent spirometry testing and completed a questionnaire on sleep, respiratory symptoms and past medical history. OSA was defined by positive answers to questions on snoring, breathing cessations and daytime sleepiness. Current asthma was defined by ever having received a physician's diagnosis of asthma and current use of anti-asthma medication. Logistic regression analyses, including interaction analyses between sex and the different explanatory variables, were used to examine associations between OSA and current asthma, pre- and post-bronchodilator pulmonary function tests, smoking habits and respiratory symptoms. All models were adjusted for age, sex, waist-hip ratio and smoking. Results OSA was more prevalent in the middle-aged compared to the elderly (6.2% vs 3.6%), and in subjects reporting respiratory symptoms. 4.8% had OSA and 6.1% had current asthma. Current asthma and the lowest quartile of post-bronchodilator FVC were significantly associated with OSA with ORs of 2.5 (1.5, 4.2) and 1.7 (1.1, 2.7), respectively. In interaction analyses, women with post-bronchodilator FEV1/FVC<0.7 had an increased risk of OSA [OR of 4.1 (1.7, 9.7)] compared to women with a FEV1/FVC >= 0.7. Conclusions Current asthma was associated with increased risk of OSA. Women with chronic airflow limitation, but not men, had increased risk of OSA.