Objective: To evaluate whether the clinical characteristics of chronic cough were helpful in determining its specific causes.
Methods: Patients with chronic cough were evaluated by a validated systematic diagnostic protocol. The patients with identified single cause were divided into 4 groups accordingly: cough-variant asthma (CVA), upper airway cough syndrome (UACS) or post-nasal drip syndrome (PNDS), eosinophilic bronchitis (EB), gastroesophageal reflux related cough (GERC), and the characteristics of the timing, character, onset and associated manifestations of chronic cough in different causes were compared.
Results: A total of 196 patients met the inclusion criteria, including 55 with EB, 45 with UACS, 50 with CVA and 46 with GERC. No significant difference was found in age, gender and course among EB, UACS, CVA and GERC. The incidence of nocturnal cough in CVA was 26.0% (13/44), significantly higher than in EB (9.1% (5/55), chi2 = 5.272, P<0.05), UACS (2.2% (1/45), chi2 = 10.657, P<0.01) and GERC (0% (0/46), chi2 = 13.833, P<0.01). The specificity of nocturnal cough for CVA was 95.9%. The sensitivity and specificity of cough associated with meals in GERC was 52.2% (24/46) and 83.3%, and regurgitation associated symptom in GERC were 69.6% (32/46) and 80.0%, which were significantly higher than other groups. The incidence of postnasal drip, rhinitis associated symptom and case history of nasal diseases in UACS were 66.7% (30/45), 88.9% (40/45) and 82.2% (37/45), and the specificity of them were 89.4%, 65.6% and 63.6% respectively.
Conclusion: The timing character and some associated symptoms of chronic cough are useful in predicting a single cause.