There is no relationship between chronic obstructive pulmonary disease and obstructive sleep apnea syndrome: a population study.

BACKGROUND: Both chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea syndrome (OSAS) are common diseases. Some recent studies suggest an increased prevalence of COPD among subjects with OSAS.

OBJECTIVES: The study objective was to evaluate whether there is an epidemiological relationship between COPD and OSAS in a random population sample.

MATERIALS AND METHODS: The study population, 356 males (53%) and 320 females, mean age 56.6+/-8.2 years (range 41-72), was selected from a voting list for parliamentary election in Warsaw. The investigation included lung diseases and smoking history with polysomnography and spirometry.

RESULTS: OSAS was diagnosed in 76 subjects (11.3%), 59 males (8.8%) and 17 females (2.5%), mean apnea/hypopnea index (AHI) was 25.3+/-16.1, mean overnight SaO2 92.1+/-3.3%, minimum SaO2 76.9+/-9.4%, and SaO2<90%=18.9+/-23.9% of total sleep time. COPD was diagnosed in 72 subjects (10.7%), 39 males and 33 females. Severity of airflow limitation was assessed according to European Respiratory Society (ERS) guidelines: mild in 70%, moderate in 22%, and severe in 8%. In 7 subjects (9.2% of OSAS population, 1% of total population) OSAS and COPD overlapped. Polysomnographic variables were compared between overlap (overlap syndrome, OS) and OSAS subjects. In the OS mean AHI was 19.0 versus 25.3 in OSAS (nonsignificant), mean SaO2 89.6 versus 92.3% in OSAS (p<0.005), and time spent in SaO2<90% was 25.4 versus 18.2% in OSAS (p=0.04).

CONCLUSIONS: COPD in subjects with OSAS was as frequent as in the general population. In the OS group mean arterial blood saturation was lower and time spent in desaturation was longer than in OSAS. The presented data suggest a more severe course of sleep-disordered breathing in subjects with coexisting COPD.