Sleep characteristics and cardio-metabolic comorbidities in the OSA-COPD overlap syndrome: Data from the European Sleep Apnea Database (ESADA)

Introduction: The combination of chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA), has been defined as overlap syndrome (OVS) and its impact on sleep quality and cardiovascular outcomes remain uncertain. Aim: To compare clinical, polysomnographic and burden of cardiovascular comorbidities in OSA vs OVS. Methods: This cross-sectional analysis included initially data from 5,600 patients with OSA and lung function in the European Sleep Apnea Database. Selected OSA (n=1109) and OVS (n=509) patients were matched (2:1) based on sex, age, body mass index (BMI), and apnea-hypopnea index (AHI) at baseline. Generalized linear mixed effects models were used to compare groups on demographic, polysomnographic and comorbidity burden. Results: Patients with OVS as compared to those with OSA were older (58.8 vs. 52.6 years, p<0.01), more often male (85.1 vs. 74.4%, p<0.01), and presented with similar Epworth Sleepiness Scale scores (10.2 vs. 10.1). In the case-control sub analysis, sleep efficiency (β -2.7 (95%CI -4.4, -1.1) and nocturnal mean oxygen saturation (SpO2) (β -1.1 (95%CI -1.5, -0.7) were lower in OVS. Sleep efficiency was associated with FEV1 and diurnal PaO2 in OVS. Hypertension (58.5% vs 53.1%), ischemic heart disease (20.0% vs 15.2%), and heart failure (11.4% vs 6.0%) were significantly more prevalent in OVS independently of confounders. Having COPD increased by 1.75 the odds of having heart failure, and the most important determinant of this link was a lower nocturnal mean SpO2. Conclusion: OVS patients presented with more sleep-related hypoxia, decreased sleep quality and a higher risk for heart failure.