Impact of Continuous Positive Airway Pressure on the Occurrence of Acute Exacerbations of COPD in Patients With COPD-OSA Overlap Syndrome (CO-OS)

Chronic Obstructive Pulmonary Disease (COPD) and Obstructive Sleep Apnea (OSA) are both frequent respiratory diseases with estimated prevalences between 8 and 15% of the adult population. Because of those high prevalences those two entities are often associated in same patients (1 to 4% of the general population). This association is then referred to as Overlap Syndrome (CO-OS). Data from observational studies suggest that this association may have an additive or even synergistic negative impact on patient's prognosis. Indeed, in a cohort of patients diagnosed as having a CO-OS, patients who did not receive specific treatment for OSA had a 76% increased risk of death compared to patients treated with continuous positive airway pressure (CPAP) and a 2-fold increased risk of acute COPD exacerbation. In another cohort of patients with both OSA and severe oxygen treated COPD, untreated patients for OSA had a 5-fold increased risk of death compared to patients treated with CPAP. There are strong signals from observational studies in support of a beneficial impact of CPAP therapy on respiratory outcomes in patients with CO-OS. However, those findings are not supported by any controlled study. It is difficult to directly transpose the observational data to current clinical practice in the context of the recent studies on the impact of CPAP on OSA prognosis. Indeed, data from similar observational OSA cohorts have reported a major impact of CPAP on the overall survival and cardiovascular outcomes in patients with OSA. Ten years later, this impact has not been confirmed by several randomized studies. To date, there is no consensus on a systematic screening and, if present, management of OSA in patients with COPD. The need for specific research on that field was emphasized in 2018 in an official American Thoracic Society Research Statement which recommends "randomized trials that compare clinical outcomes among patients with Overlap Syndrome whose OSA is treated to clinical outcomes among patients with Overlap Syndrome whose OSA is untreated".