Persistent Cough in Nonsmokers

OBJECTIVE: The purpose of this study was to test the hypothesis that, using Irwin′s protocol, the majority of nonsmokers with persistent cough can be diagnosed and treated successfully. DESIGN: Retrospective review of patients referred for the investigation of chronic cough. SETTING: Referral out‐patient practice of a hospital‐based pulmonary physician. PATIBNTS: There were 228 patients who satisfied the following entry criteria for inclusion in the data analysis: cough longer than four weeks; nonsmoker; normal chest radiograph; and completion of the required investigations. A total of 198 patients completed the required investigations and returned for the final follow‐up visit. INTERVENTIONS: Diagnostic tests included chest radiographs, pulmonary function tests, radiographs of the sinuses, barium swallow and fibreoptic bronchoscopy. MAIN OUTCOME MEASURES: Status of cough at the time of final follow‐up visit, classified according to four levels: resolved, improved, unchanged or worse. RESULTS: The diagnosis was established in 91 % of patients. The most common diagnoses (alone or in combination) were postnasal drip (26% ), asthma (25% ), gastroesophageal reflux (24%), postinfectious cough (21 %), and cough due to angiotensin‐converting enzyme inhibitors (6%); none had an occult malignancy and one patient had endobronchial tuberculosis. The initial diagnostic impression was best in patients with postinfectious cough (100%) and worst in patients with asthma (25%). The outcome of specific therapy was successful in 91 % of patients. CONCLUSIONS: In the majority of nonsmoking adults cough can be diagnosed and treated successfully. most causes are relatively ′benign′ and the initial clinical impression may be quite misleading, particularly in cough‐variant asthma.