A Randomized, Controlled, Pilot Study of CPAP for Patients with Chronic Cough and Obstructive Sleep Apnea

Abstract

An association between chronic cough and obstructive sleep apnea (OSA) has been reported in prior studies with resolution or improvement in cough after continuous positive airway pressure (CPAP) therapy. Controlled studies of the benefit of CPAP on cough-quality of life measures have not been conducted. Does CPAP therapy for OSA improve cough in patients with chronic unexplained cough? Patients with unexplained chronic cough (> 2months duration of cough) and OSA were randomized to receive either CPAP or sham CPAP therapy for 6weeks. The primary end point was the change in health status assessed with the Leicester Cough Questionnaire (LCQ) in patients treated with CPAP vs. sham CPAP. Secondary end points were changes in exhaled breath condensate markers of airway inflammation (interleukin-6, nitrite/nitrates, hydrogen peroxide and 8-isoprostanes). A total of 22 patients with chronic unexplained cough and OSA were randomized of whom18 completed 6weeks of treatments with either CPAP or sham CPAP. The CPAP vs. sham CPAP-treated group were comparable in terms of sex distribution, body mass index, and OSA severity. Following CPAP therapy, there was a significantly greater improvement in total LCQ scores as compared to those treated with sham therapy (ANCOVA p value 0.016). No significant differences were noted in the exhaled breath condensate marker changes between CPAP-treated vs. sham CPAP-treated groups. Treatment of comorbid OSA in patients with chronic cough improved cough quality of life measures following treatment of OSA with CPAP in this pilot study. Larger studies to understand this association and unravel mechanisms of CPAP benefit in chronic cough need to be undertaken. Clinical Trial Registration NCT03172130.