The global epidemiology of chronic cough in adults: a systematic review and meta-analysis.

Cough is an essential defence mechanism [1]. However, chronic cough is a significant cause of morbidity, seriously impairing quality of life [2]. Previously, chronic cough was considered a consequence of various diseases, such as asthma/eosinophilic bronchitis, rhinitis and gastro-oesophageal acid reflux disease [3, 4]. Recent evidence, however, suggests that chronic cough is a clinical syndrome with distinct intrinsic pathophysiology characterised by neuronal hypersensitivity [5–7]. Here, we estimated the worldwide epidemiological burden of chronic cough irrespective of putative diagnosis in general adult populations using a comprehensive systematic literature review.