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

INTRODUCTION: 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.