[Etiology and a diagnostic protocol for patients with chronic cough]

The spectrum and frequency of causes and the diagnostic protocol for chronic cough were explored.

A total of 194 patients with at least 3 weeks of chronic cough and normal chest radiographs were recruited from the outpatient clinic of Guangzhou Institute of Respiratory Diseases between July 2003 to June 2004. The causes were investigated using a well-established protocol. The diagnostic protocol included history inquiring and physical examination, pulmonary function tests, induced sputum cell differentials, 24 h esophageal pH monitoring, CT of the paranasal sinuses or chest, fiberoptic rhinoscopy or bronchoscopy. The final diagnosis was made based on clinical manifestation, examination findings and a positive response to therapy.

The cause of chronic cough was defined in 95.4% of the patients, with a single cause found in 153 patients (82.7%), and multiple causes in 32 patients (17.3%). The five most important causes of cough were: eosinophilic bronchitis (n = 51, 22.4%), rhinitis and/or paranasal sinusitis (PNDs, n = 39, 17.1%), cough-variant asthma (n = 31, 13.6%), atopic cough (n = 28, 12.3%), and gastroesophageal reflux (n = 27, 11.8%).

The spectrum and frequency of causes of chronic cough in our study is different from the previous reports in western countries. Eosinophilic bronchitis and atopic cough are important causes of chronic cough. A modified diagnostic protocol was established accordingly.