Correlation between chronic obstructive pulmonary disease and obstructive sleep apnea syndrome in a general population in Iran*

BACKGROUND: The aim of this study was to evaluate epidemiological relationship between chronic obstructive pulmonary disease and sleep apnea syndrome in a sample of Persian population. METHODS: As a part of a population-based cross-sectional study, 3900 randomly selected individuals aged 15 years or older were invited to take part in the survey; 3770 individuals (96.6%) agreed to fill out the respiratory and sleep questionnaire. Those subjects suspected to have either chronic obstructive pulmonary disease and/or obstructive sleep apnea underwent spirometry and polysomnography test if indicated. Spirometric measurements were performed on 420 invited responders. Polysomnography measurements were performed on 25 of the responders. RESULTS: Prevalence rates for sleep apnea, chronic obstructive pulmonary disease and current asthma were 4.98%, 5.7% and 3.1%, respectively. Logistic regression showed independent associations between sleep apnea and chronic obstructive pulmonary disease. There was no significant independent association between sleep apnea symptoms and current asthma and wheeze ever. CONCLUSIONS: These observations indicated relationship between chronic obstructive pulmonary disease and obstructive sleep apnea. These observations indicated the necessity of further studies to explain the possible common pathogenic mechanisms involved in two disease entities.