One of the most common etiologies of chronic cough is gastroesophageal reflux disease (GERD). In up to 75 percent of patients with GERD, chronic cough is the only presenting symptom. In addition, chronic cough caused by other etiologies may lead to GERD. Cough related to GERD can be diagnosed using a 24-hour ambulatory esophageal pH monitor, although this procedure is expensive and may be poorly tolerated by patients. In one study, GERD-related cough improved with the use of a high-dose proton pump inhibitor. Poe and Kallay evaluated the use of proton pump inhibitor therapy, with or without the addition of a prokinetic agent, in the diagnosis and treatment of GERD-related cough.
The study included all patients with chronic cough who were referred to a university-based pulmonary clinic. Chronic cough was defined as a cough lasting three or more weeks. Patients with normal results on chest radiography were evaluated for the three most common causes of cough—postnasal drip syndrome, asthma, and GERD. The evaluation was performed using an anatomic diagnostic protocol. When symptoms other than cough were present, the initial evaluation was based on those symptoms. If no symptoms suggested a cause of chronic cough, investigators used a methacholine challenge test and an empiric trial of an antihistamine-decongestant to diagnose asthma or postnasal drip syndrome.
The remainder of patients thought to have GERD-related cough were placed on a once-daily dosage of a proton pump inhibitor. Patients who were thought to have esophageal dysfunction or who had an inadequate response to the proton pump inhibitor received a prokinetic agent. Those who did not respond to this treatment plan underwent a 24-hour esophageal pH-monitoring test.
Of the 183 patients with chronic cough, 56 were identified as having GERD-related chronic cough. In this trial, 43 percent of patients with GERD-related cough had GERD as the only cause of chronic cough. In addition, 43 percent of patients with GERD-related chronic cough had cough as their only presenting symptom. The majority of patients responded to proton pump inhibitor therapy alone or in combination with a prokinetic agent. The chronic cough was eliminated or improved dramatically in 86 percent of patients after four weeks of therapy. The 12 patients who did not respond were evaluated with 24-hour esophageal pH monitoring; nine patients were found to have some cough episodes during reflux, while three patients had reflux unrelated to their chronic cough. Six of the nonresponders had aspiration diagnosed by bronchoscopy.
The authors conclude that four to six weeks of therapy with a proton pump inhibitor, with or without the addition of a prokinetic agent, successfully diagnoses and treats the vast majority of patients with GERD-related cough. In patients who do not respond to this therapy, 24-hour esophageal pH monitoring can be used to establish reflux as the cause of chronic cough. Nonresponders are also at a higher risk of aspiration.