Patients with chronic cough are frequently seen by physicians, but the condition is difficult to evaluate and treat. Recent studies have suggested that in certain patients, cough is related to gastroesophageal reflux disease (GERD). In some cases of GERD, chronic cough may be the only presenting symptom. The issue facing physicians is how to evaluate patients in whom other common causes of chronic cough have been ruled out. Ours and colleagues evaluated the prevalence of acid reflux–induced chronic cough, the ability of esophageal testing to identify gastroe-sophageal reflux–induced cough and the usefulness of a proton pump inhibitor in evaluating these patients.
Seventy-one patients who were diagnosed with chronic cough were enrolled in the study. The participants were evaluated initially with a chest radiograph, methacholine challenge tests and empiric treatment for postnasal drip. They were then asked to keep a cough diary, noting the frequency and severity of their cough on a graded scale. Those who had other causes of chronic cough were excluded, and the remaining patients underwent esophageal and pH testing. Those who were positive for GERD were randomized to receive 40 mg of omeprazole or placebo twice a day for 12 weeks. Patients whose pH monitor test was negative were treated with open-label omeprazole for 12 weeks. Follow-up was continued for one year.
Twenty-three (33 percent) of the participants were included in the esophageal monitoring and pH evaluation phase of the study. Of these 23, 17 patients (74 percent) had abnormal pH tests, and 10 patients (43 percent) had abnormal esophageal motility results. Of the patients with abnormal esophageal study results, only a small percentage responded to omeprazole therapy. In patients with positive pH studies, 26 percent improved with omeprazole therapy, and this improvement extended for a full year.
The authors conclude that esophageal testing did not reliably predict which patients would respond to proton pump inhibitor therapy. The best diagnostic and therapeutic approach in patients who have had other causes of chronic cough excluded is empiric treatment for two weeks with a high dosage of a proton pump inhibitor.