The Etiologic Diagnosis of Chronic Cough in Patients Attending a University Affiliated Cough Clinic

Dear Editor, Cough is one of the most common complaints for which patients seek medical attention. In order to determine the etiologic diagnosis of chronic cough in our patients and to find out our success rate in the diagnosis and treatment of these patients, 100 consecutive patients with the chief complaint of chronic cough, who attended the cough clinic in our center, were evaluated; each patient was followed for at least 6 months. The diagnostic procedure was based on the anatomic protocol for diagnosing chronic cough designed by Irwin. A combination of history, physical examination, and laboratory findings to evaluate possible causes of cough were considered. The suspected cause could be confirmed if the cough resolved or significantly improved after a trial of diagnosis specific treatment. Fifty-five percent of patients were female and 45% were male. Their mean± SD age was 45.13±17.43. Seventy-one percent were non-smokers, 13% passivesmokers, 9% ex-smokers, and only 7% of them were active smokers. Two patients were on Angiotensin Converting Enzyme Inhibitor (ACE-inhibitor) drugs. Sixty-three percent of patients complained of postnasal discharge, while 56% of them had dyspnea, and 6 patients suffered from heart burn. The etiology of chronic cough was determined in all of our patients. In 15% of patients, two causes were responsible simultaneously. The final diagnoses are shown in Table 1. The most common etiologies of chronic cough were upper airway cough syndrome (due to Post Nasal Discharge (PND)), asthma and Gastro-Esophageal Reflux Disease (GERD). 3-8 However, a number of other etiologies should be considered in patients presenting chronic cough. Postinfectious cough, complication of drug therapy (i.e. ACE inhibitors), airway disease (chronic bronchitis, bronchiectasis, neoplasm, foreign body), pulmonary parenchymal disease (interstitial lung disease, lung abscess), are samples of chronic cough etiologies with lower prevalence. As it is evident from this study, by following the anatomic diagnostic protocol, a cause for cough can be found in almost all cases. Thus, systematic evaluation remains the most effective approach to chronic cough and diagnosis-based treatment is the best way to manage it. Fifty-five percent of patients in our study were female. It has been shown that women are more likely than men to develop chronic cough, because they have more sensitive cough reflex than men. In our study, PND syndromes and asthma either alone or both together accounted for the most cases of chronic cough, and this is in accordance with the results of other studies in this field. Underlying etiologies of PND include allergic, perennial nonallergic and vasomotor rhinitis, acute nasopharyngitis, and sinusitis. Asthma is the second leading cause of persistent