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Camden, NJ
Dr. Pratter is Full Professor and Dr. Abouzgheib is a Clinical Instructor, Robert Wood Johnson School of Medicine at Camden, NJ.
Correspondence to: Melvin R. Pratter, MD, FCCP, Cooper University Hospital, Suite 312, 3 Cooper Plaza, Camden, NJ 08103; e-mail: pratter-melvin{at}cooperhealth.edu
Cough is an important medical and economic problem. It is a common symptom of a number of respiratory and nonrespiratory disorders. It has a substantial impact on health; it represents the most common symptom leading patients to consult with their doctor.1
Traditionally, cough has been categorized as follows based on duration: acute cough, lasting < 3 weeks; subacute cough, lasting 3 to 8 weeks; and chronic cough, lasting > 8 weeks.2 Most of the published studies on cough have concentrated on chronic cough. In this issue of CHEST (see page 1142), Kwon et al3 make an important contribution and fill a void in the literature by prospectively looking at the causes of subacute cough. They report on 529 patients with a complaint of cough from Seoul, Korea, but focus on the 184 patients who met the criteria for subacute cough. Their initial approach included obtaining a medical history, and performing a physical examination, pulmonary function studies, including a methacholine bronchoprovocation challenge (BPC), chest roentgenogram, and an induced sputum test measuring eosinophils. No initial therapy was given. Patients were seen 7 to 10 days later. Cough had spontaneously resolved in 62 of 182 patients (34%). A diagnosis of "postinfectious cough," based on predefined criteria, was given to most patients with spontaneously resolving cough (74.3%).
At the second visit, 122 patients continued to complain of cough. In 97 of 122 patients, cough was thought to occur either secondary to postnasal drip (72 patients) or after infection (25 patients), and those patients were treated with a first-generation antihistamine-decongestant (chlorpheniramine, 4 mg, and pseudoephedrine, 30 mg three times per day) for 3 weeks. Sixty-eight of 97 patients (70%) showed significant improvement with the antihistamine-decongestant therapy. In the 29 patients who did not respond (plus 25 patients who initially had no findings of postnasal drip or postinfectious cough), the results of BPC analysis and induced sputum testing were reviewed. Thirty-eight of 54 patients had a positive results for BPC, induced sputum testing, or both, and all but 3 of these patients responded to therapy with inhaled corticosteroids. Cough-variant asthma was diagnosed in patients with a positive BPC finding, and eosinophilic bronchitis was diagnosed in those patients with a negative BPC finding but eosinophils measured on sputum samples. The 16 remaining patients with negative BPC and sputum (plus the 3 patients who did not respond to therapy with inhaled corticosteroids) underwent 24-h esophageal pH monitoring, CT scan of the chest, and bronchoscopy.
The authors came to several conclusions: One, cough after infection is the most common cause of subacute cough (48%), postnasal drip is the second most common (33%), and cough-variant asthma is the third most common (16%). Second, in a significant percentage of patients with subacute cough (34%), it is self-limited and will resolve without treatment. Third, most patients with subacute cough that spontaneously resolves had postinfectious cough (74%). The authors recommend that BPC be delayed until after an initial period of either no treatment or antihistamine-decongestant treatment for postnasal drip (unless asthma was strongly suspected).
Although we think that this study of subacute cough is a valuable contribution to the literature, we believe that some of their results are subject to a different interpretation. We think that the distinction between postinfectious cough and postnasal drip-induced cough is not nearly as clear-cut as they suggest. In this study, cough was diagnosed as being postinfectious when the etiology was believed to have been an upper respiratory tract infection (ie, a "common cold"). Because the best available evidence suggests that the predominant mechanism of acute cough from the common cold is postnasal drip,4 it is quite likely that many of the subacute coughs categorized as being postinfectious could alternatively have been due to a lingering postnasal drip. Furthermore, it has been reported that the diagnosis of postnasal drip (or at least cough responsive to antihistamine-decongestant therapy) cannot be eliminated based on a lack of symptoms or signs because up to 20% of patients whose cough responds to antihistamine-decongestant therapy have no manifestations of postnasal drip (called silent postnasal drip).5
Second, while it is helpful to know that subacute cough may resolve spontaneously, it does not follow that treatment with an antihistamine-decongestant should be withheld. Patients with cough are seeking help for a bothersome symptom. Because it is not possible to predict in which patients subacute cough will spontaneously resolve or how long it might take, it does not make sense to withhold treatment. The patient is suffering from the cough. The "up-front" use of an antihistamine-decongestant frequently abbreviates the cough with minimal side effects.45 Therefore, the decision not to treat because cough might resolve over time is not an optimal approach. We recommend that a first-generation antihistamine-decongestant (our choice is sustained release brompheniramine, 12 mg, and pseudoephedrine, 120 mg every 12 h) be administered as the initial therapy whatever the duration of cough, unless there is a contraindication to one of these drugs. This empiric approach makes sense because postnasal drip syndromes appear to be the most common causes of cough; this approach has been shown to work in patients with acute cough,4 subacute cough,3 and chronic cough.25 If 2 weeks of therapy is ineffective, we would proceed with a BPC. Many of these patients will have either cough-variant asthma or virus-induced transient airway hyperresponsiveness. As the results of the study by Kwon et al3 show, a positive BPC result is predictive of a positive response to therapy with inhaled corticosteroids. If BPC is unavailable, then an empiric course of inhaled corticosteroids is reasonable because it will treat cough-variant asthma, transient virus-induced airway hyperresponsiveness, and eosinophilic bronchitis.
We agree that when a patient seeks medical attention because of a troublesome cough, the goal of making a specific etiologic diagnosis is desirable. It is important for the physician to remember, however, that usually the primary objective for the patient is eliminating this highly disruptive symptom as quickly as possible. The up-front use of first-generation antihistamine-decongestant therapy helps to facilitate both goals. Indeed, in the just released new guidelines on cough from the American College of Chest Physicians,6 the initial use of antihistamine-decongestant therapy as both a diagnostic and therapeutic trial for cough is recommended in most cases.
Based on the new cough guidelines, there are two other points that we would like to emphasize. Because it is not known whether upper airway disease causes cough through the final common pathway of postnasal drip or whether, in fact, in some circumstances they cause irritation or inflammation of upper airway structures that directly stimulate cough receptors and produce cough independently or in addition to any associated postnasal drip, the guidelines recommend that the term upper airway cough syndrome replace the term postnasal drip syndrome.7 Moreover, unless the upper airway cough syndrome is histamine-mediated (ie, allergic), the guidelines recommend that first-generation antihistamines with anticholinergic activity be the antihistamines of choice. With respect to cough due to the common cold, the first-generation antihistamines have been effective, while the new, relatively nonsedating antihistamines have not been effective.8
Footnotes
Neither Dr. Pratter nor Dr. Abouzgheib has any financial or any other personal conflict of interest with any organizations with a financial interest in this subject matter.
References
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