PREDICTIVE VALUES OF THE CHARACTER, TIMING, AND COMPLICATIONS OF CHRONIC COUGH IN DIAGNOSING ITS CAUSE

Background: It is not clear whether careful history taking with detail ed questioning of the characteristics of cough is diagnostically usefu l. Objective: To determine if the character, timing, or complications of chronic cough were helpful in determining its cause. Methods: A pro spective, descriptive study of consecutive, unselected, immunocompeten t patients referred to our university outpatient clinic because of chr onic cough. All patients were evaluated by a previously published and validated systematic diagnostic protocol, a self-administered question naire, and by observing the character of involuntary and voluntary cou ghs. The final diagnosis of the cause of cough required fulfillment of pretreatment criteria plus having cough disappear or substantially im prove as a complaint with specific therapy. Results: Eighty-eight pati ents met inclusion criteria and were fully evaluated. The mean+/-SD ag e was 53.1+/-16 years (range, 15-83 years) and 24 were males and 64 we re females with a mean+/-SD history of cough for 6.6+/-9.8 years (rang e, 1 month-44 years). The cause of chronic cough was established in 86 (98%) of 88 patients. Eighty-one (92%) of 88 had cough disappear as a complaint. Cough was as a result of a single cause in 39% and multipl e causes in 59%. Gastroesophageal reflux disease, postnasal drip syndr ome, and asthma were the 3 most common causes of chronic cough and acc ounted for 90% of diagnoses. Gastroesophageal reflux disease, postnasa l drip syndrome, and asthma were again found to be the 3 most common c auses of chronic cough irrespective of patient estimated quantity of d aily sputum production. These 3 conditions caused chronic cough in 99. 4% of patients with the following characteristics: (1) nonsmoker; (2) not receiving an angiotensin-converting enzyme inhibitor drug; and (3) normal or nearly normal and stable chest radiograph. With respect to the spectrum and frequency of diagnoses and their interrelationships w ith the character, timing, and complications of cough, multiple stepwi se linear regression analysis showed that none of the variability of t he character, timing, or complications of cough could be explained by any specific diagnosis. Conclusions: A carefully taken history with de tailed questioning of the character, timing, and complications of chro nic cough is not likely to be useful in diagnosing the cause of cough. The cause can be determined and successfully treated with specific th erapy in the greatest majority of cases. Chronic cough is often caused by multiple, simultaneously contributing causes. Postnasal drip syndr ome, asthma, and gastroesophageal reflux disease remain the 3 most com mon causes of chronic cough and there is a clinical profile that nearl y always predicts their presence in immunocompetent patients.