Chest
Volume 104, Issue 5, November 1993, Pages 1511-1517
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Clinical Investigations: Miscellaneous: Clinical Trial: Journal Article: Randomized Controlled Trial
Chronic Cough Due to Gastroesophageal Reflux: Clinical, Diagnostic, and Pathogenetic Aspects

https://doi.org/10.1378/chest.104.5.1511Get rights and content

Background

Gastroesophageal reflux (GER) is a common cause of chronic cough. Moreover, chronic cough can be the sole presenting manifestation of GER disease (GERD). It has been suggested recently that GER most often causes chronic cough by stimulating the distal esophagus. To gain further diagnostic and pathophysiologic knowledge, we prospectively evaluated a group of patients with chronic cough likely to be due to GER with extensive gastrointestinal and respiratory studies and then observed their response to antireflux therapy.

Methods

We prospectively characterized 12 subjects whose chronic cough was likely to be due to GER by chest radiographs, barium esophagography, 24-h esophageal pH monitoring (EPM) with probes in the distal and proximal esophagus, esophagoscopy, and bronchoscopy. Then, prior to instituting antireflux therapy, we objectively counted coughs during the distal esophageal infusion of 0.1 N HCl or 0.9 percent saline solution administered in a randomized, double-blind, standardized fashion (ie, Bernstein acid-perfusion test).

Results

Gastroesophageal reflux was determined to cause cough in all subjects based on disappearance of cough with antireflux therapy. It was clinically “silent” in 75 percent. The EPM was the test most frequently abnormal (sensitivity, 92 percent). Distal esophageal data revealed that 10 of 12 subjects had GER-induced coughs (12±12) while only 7 of 12 had an abnormal esophageal pH conventional parameter (eg, percent time pH <4). Compared with the distal esophagus, GER to the proximal esophagus occurred (p=0.017) and induced cough (p = 0.004) less often. Compared with baseline (9.3 ± 17.6), there were no differences in coughs induced by the infusion of saline solution (9.2 ±15.9) or acid (15.1 ±26.7); the number of coughs induced by acid was negatively correlated with distal esophageal acid-GER events during EPM (r = −0.64, p=0.01). Neither bronchoscopy nor chest radiographs were consistent with aspiration.

Conclusions

There is a clinical profile that prospectively predicts which patients have chronic cough due to GER. The cough was most likely due to stimulation of the distal esophagus, not aspiration. Intraesophageal acid is unlikely to be the sole mediator in gastric juice causing the cough. While EPM is the single most helpful diagnostic test, conventionally utilized diagnostic indices of GERD can be misleadingly normal; observing GER-induced coughs is more frequently helpful.

Section snippets

Study Design

First, we prospectively and fully characterized immunocompetent patients from upper gastrointestinal as well as respiratory standpoints who were consecutively referred with chronic cough of unknown cause and whose cough was deemed likely to be due to GER after a standard diagnostic workup.1, 4 Second, we objectively counted coughs during the distal esophageal infusion of 0.1 N HCl or 0.9 percent saline solution administered in a randomized, double-blind, standardized fashion.6 Third, we

Characteristics of Study Group

From Dec 11, 1989 to Sept 4, 1990, 12 consecutive and unselected patients who were referred for evaluation and whose chronic cough remained persistent after a standard diagnostic workup underwent our study protocol. Each had normal or near-normal chest radiographs; none were smoking or taking an angiotensin-converting enzyme inhibitor; none had their coughs disappear with specific treatment for postnasal drip syndrome and/or asthma; and all had abnormal prolonged EPM sessions and/or barium

Discussion

From our study on this well-characterized, homogeneous group of patients, five findings emerged that expand our clinical and pathophysiologic knowledge as well as pathogenetic understanding of chronic cough due to GER.

First, we have reconfirmed that GER can be the sole cause of chronic cough1, 2, 3, 4, 5 and that chronic cough can be the sole presenting manifestation of GERD.2 This was based on laboratory studies (eg, prolonged EPM and barium esophagography) that were consistent with GER as the

ACKNOWLEDGMENTS

The authors thank Peter I. Hoffman, R.R.T., and Stephen E. Olson, R.R.T., for their technical assistance.

References (18)

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Presented in part at the Annual Meeting of the American Thoracic Society, Anaheim, Calif, May 15, 1991 (Am Rev Respir Dis 1991; 143, p 2: A534).

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