RESULTS: Between 2004 and 2011, 134,752 patients with COPD were included. Of these 12,730 (9.4%) had coexisting OSA i.e. overlap syndrome. The prevalence of overlap syndrome in patients with COPD increased from 4.5% in 2004 to 10.5% in 2011 (p-value of trend <0.001). The largest increases in overlap syndrome during the study period was seen in age group 66-74 years, female gender, and those with 3 or more comorbidities. Patients with overlap syndrome had higher rates of obesity, hypertension, congestive heart failure, diabetes, hyperlipidemia and coronary artery disease compared to those with COPD alone.