CHRONIC COUGH WITH A HISTORY OF EXCESSIVE SPUTUM PRODUCTION - THE SPECTRUM AND FREQUENCY OF CAUSES, KEY COMPONENTS OF THE DIAGNOSTIC EVALUATION, AND OUTCOME OF SPECIFIC THERAPY

Study objective: To determine (1) the spectrum and frequency of causes of chronic cough with a history of excessive sputum production (CCS) and (2) the response of these causes to specific therapy. Study design : Prospective study utilizing the anatomic diagnostic protocol origina lly developed to diagnose chronic cough. Patients: Seventy-one immunoc ompetent adults who complained of expectoration of greater than 30 mt of sputum per day. Location: University hospital pulmonary outpatient clinic. Results: Patients were seen an average of 4.2 times over 4.6 m onths before a specific diagnosis was made, The cause of CCS was deter mined in 97%, It was due to one cause in 38%, 2 in 36%, and three in 2 6%, Postnasal drip syndrome (PNDS) was a cause 40% of the time, asthma 24%, gastroesophageal reflux disease (GERD) 15%, bronchitis 11%, bron chiectasis 4%, left ventricular failure 3%, and miscellaneous causes 3 %. Among patients with a normal chest radiograph who were nonsmokers a nd not taking an angiotensin converting enzyme inhibitor, CCS was due to PNDS, or asthma, or GERD, or all three in 100% of cases. Chest radi ograph, methacholine inhalation challenge, 24-h esophageal pH monitori ng, bronchoscopy, and spirometry with bronchodilator each had a sensit ivity and negative predictive value of 100%, Chest radiograph and bari um swallow had positive predictive values of only 38% and 30%, respect ively. Conclusions: (1) The anatomic diagnostic protocol for cough is also valid for CCS; (2) the major causes of chronic excessive sputum p roduction and chronic cough are so similar that CCS should be consider ed a form of chronic cough; (3) the evaluation of CCS is more complica ted and takes longer than the evaluation of chronic cough; (4) the maj or strength of the laboratory diagnostic protocol is that it reliably rules out conditions; (5) the outcome of specific therapy is almost al ways successful; and (6) the term ''bronchorrhea'' can be misleading i f it is applied to excessive sputum production before a specific diagn osis of its source is made since the most common cause of excessive sp utum that is expectorated (PNDS) is a disorder of the upper respirator y tract. Therefore, nonspecific therapies theoretically aimed at reduc ing mucus production in the lower respiratory tract are not likely to be helpful.