Does Continuous Positive Airway Pressure (CPAP) treatment of obstructive sleep apnoea (OSA) improve asthma-related clinical outcomes in patients with co-existing conditions?- A systematic review

Introduction: A high prevalence of OSA has been observed in asthma populations, with detrimental impact on clinical outcomes. Aim: To determine if CPAP treatment of co-existing OSA improves asthma-related symptoms and quality of life. Methods: Literature review of EMBASE and MEDLINE databases prior to July 2017. Study populations included asthmatics with co-existing OSA treated with CPAP, and >= 1 asthma-related clinical outcome measure. Results: 12 studies; 8 prospective quasi-experimental and 4 observational. Mean CPAP duration; 19.5 (2-100) weeks. Meta-analysis demonstrated significant improvement in mean Asthma Quality of Life Questionnaire scores (AQLQ and mini-AQLQ); 0.59 (95%CI; 0.25, 0.92), p = 0.0006. No significant improvement was demonstrated in forced expiratory volume in 1 s (FEV1)% predicted; 0.32 (95% CI; -2.84, 3.47), p = 0.84. Asthma Control Test/Asthma Control Questionnaire improved in 2 studies, with no improvement in 1 study. 4 studies demonstrated improvement in asthma daytime/night-time symptoms, and 3 studies showed improved asthma severity. Conclusion: Asthmatics with co-existing OSA can experience improved quality of life with CPAP treatment. This effect appears more pronounced in severe OSA or poorly controlled asthma.