Sleep and cardiometabolic comorbidities in the obstructive sleep apnoea–COPD overlap syndrome: data from the European Sleep Apnoea Database

Abstract

AimThe impact of obstructive sleep apnoea (OSA)–COPD overlap syndrome (OVS) on sleep quality and cardiovascular outcomes has not been fully explored. We aimed to compare clinical and polysomnographic characteristics of patients with OVSversuspatients with OSA, and to explore pathophysiological links between OVS and comorbidities.Study design and methodsThis cross-sectional analysis initially included data from 5600 patients with OSA and lung function in the European Sleep Apnoea Database. Two subgroups of patients with OSA (n=1018) or OVS (n=509) were matched (2:1) based on sex, age, body mass index and apnoea–hypopnea index at baseline.ResultsAfter matching, patients with OVS had more severe hypoxia, lower sleep efficiency and presented with higher prevalences of arterial hypertension, ischaemic heart disease and heart failure compared with patients with OSA. OVS was associated with a significant decrease in sleep efficiency (mean difference (β) −3.0%, 95% CI −4.7 to −1.3) and in nocturnal mean peripheral oxyhaemoglobin saturation (SpO2) (β −1.1%, 95% CI −1.5 to −0.7). Further analysis revealed that a decrease in forced expiratory volume in 1 s and arterial oxygen tension was related to a decrease in sleep efficiency and in mean nocturnalSpO2. A COPD diagnosis increased the odds of having heart failure by 1.75 (95% CI 1.15–2.67) and systemic hypertension by 1.36 (95% CI 1.07–1.73). Nocturnal hypoxia was strongly associated with comorbidities; the mean nocturnalSpO2and T90 (increase in time belowSpO2of 90%) were associated with increased odds of systemic hypertension, diabetes and heart failure but the oxygen desaturation index was only related to hypertension and diabetes.ConclusionPatients with OVS presented with more sleep-related hypoxia, a reduced sleep quality and a higher risk for heart failure and hypertension.