Burden of Comorbidities in Patients with OSAS and COPD-OSAS Overlap Syndrome.

: Obstructive sleep apnea syndrome (OSAS) and chronic obstructive pulmonary disease (COPD) are usually associated with multi-morbidity. The aim of this study was to retrospectively investigate the prevalence of comorbidities in a cohort of patients with OSAS and COPD-OSAS overlap syndrome (OS) patients and to explore differences between these two groups. : Included were consecutive OS patients and OSAS patients who had been referred to our sleep laboratory, and were matched in terms of sex, age, BMI, and smoking history. Presence of comorbidities was recorded based on their medical history and after clinical and laboratory examination. : The two groups, OS patients ( = 163, AHI > 5/h and FEV/FVC < 0.7) and OSAS patients ( = 163, AHI > 5/h, and FEV/FVC > 0.7), did not differ in terms of apnea hypopnea index ( = 0.346), and oxygen desaturation index ( = 0.668). Compared to OSAS patients, OS patients had lower average SpO ( = 0.008) and higher sleep time with oxygen saturation <90% ( = 0.002) during sleep, and lower PaO ( < 0.001) and higher PaCO ( = 0.04) in wakefulness. Arterial hypertension was the most prevalent comorbidity for both OS and OSAS, followed by dyslipidemia, cardiovascular disease (CVD) and diabetes. OS was characterized by a higher prevalence of total comorbidities (median (IQR):2 (1-3) vs. 2 (1-2), = 0.033), which was due to the higher prevalence of CVD ( = 0.016) than OSAS. No differences were observed in other comorbidities. : In OS patients, nocturnal hypoxia and impaired gas exchange in wakefulness are more overt, while a higher burden of CVD is observed among them in comparison to sex-, age- and BMI-matched OSAS patients.