Chronic cough and OSA: a new association?

Chronic cough is defined as cough lasting more than 2 months. Common causes for chronic cough in nonsmokers with normal chest radiographs and pulmonary functions include gastroesophageal reflux disease (GERD), cough-variant asthma (CVA), and upper airway cough syndrome (UACS). Current guidelines recommend diagnosing the etiology of chronic cough based upon the results of therapy for suspected GERD, CVA, and UACS. Despite following current recommendations for diagnosis and treatment, the cause for a significant proportion of chronic cough remains unexplained.Recent reports indicate the resolution of chronic cough following treatment of concomitantly diagnosed obstructive sleep apnea (OSA). Whether this represents a co-occurrence of two commonly prevalent disorders or a pathophysiologic relationship between OSA and cough remains unknown. This review offers insights into a pathophysiologic link between OSA and the commonly purported etiologies for cough, namely, GERD, UACS, and CVA. In addition, evidence for a relationship between airway inflammation that can trigger or perpetuate cough and OSA is discussed. This review explores mechanisms by which nocturnal continuous positive airway therapy resolves cough by improving underlying airway inflammation secondary to OSA and impacts upon GERD, CVA, and UACS.