Predictive factors for COPD exacerbations and mortality in patients with overlap syndrome

Patients with chronic obstructive pulmonary disease (COPD) and obstructive sleep apnoea (OSA)—overlap syndrome—have a substantially greater risk of morbidity and mortality, compared to those with either COPD or OSA alone. Objectives The aim of this retrospective study was to identify clinical modifiable factors associated with COPD exacerbations and all‐cause mortality in patients with overlap syndrome. Methods The electronic records of patients with simultaneous COPD and OSA who had a documented acute exacerbation of COPD during a 42‐month period were evaluated for reviewed. A control group of overlap syndrome patients without exacerbations was matched 1:1 for age and body mass index. Vital status and cause of death were assessed through the population death registry. Results Out of 225 eligible cases, 92 patients had at least one episode of COPD exacerbation. There was no significant association between severity of airflow limitation and apnoea hypopnea index ( P  = .31). After adjusting for confounding variables, patients who had at least one COPD exacerbation were more likely to be active smokers ( P  = .01), have poorer lung function ( P  = .001) and less likely to adhere to continuous positive airway pressure (CPAP) use ( P  = .03). All‐cause mortality was also correlated with low forced expiratory volume in 1 second ( P  = .006), CPAP use ( P  = .007), and burden of comorbidities ( P  < .001). Conclusion Lung function and CPAP use were independent predictors of COPD exacerbations and all‐cause mortality in a cohort of patients with overlap syndrome. These factors should be taken into account when considering the management and prognosis of these patients.