Esophageal pH testing in patients refractory to proton pump inhibitor therapy

Proton pump inhibitors (PPIs) are the most potent drugs available for the management of gastroesophageal reflux disease (GERD). Ambulatory 24 h pH monitoring is often recommended for patients experiencing symptoms despite PPI therapy. Recent pivotal data suggest that pH studies are predictably normal in this setting, casting doubt on the clinical utility of the current practice.

To describe 24 h pH findings in patients referred by gastrointestinal specialists for the indication of GERD refractory to PPI therapy.

A retrospective review was performed, examining all patients undergoing ambulatory esophageal pH monitoring at the St Boniface General Hospital Motility Laboratory, between January 2002 and June 2005. Tests performed in patients clinically suspected of having GERD who were not responding to PPI therapy formed the study group. pH data were analyzed for the total, upright and supine periods. Abnormal reflux parameters were defined by applying three criteria: DeMeester score greater than 14.72; pH less than 4.0 more than 5.5% of the total time, more than 8.3% of the time upright or more than 3% of the time in the supine position; and pH less than 4.0 for more than 1.6% of the total time.

A total of 417 patients underwent pH monitoring during the time of the review. One hundred seven patients (mean age 51.7 years; 37 men and 70 women) met study criteria. Sixty-eight (63.6%) were referred by a gastroenterologist and 39 (36.4%) were referred by a gastroenterologist surgeon. Sixty-one patients were on twice-daily PPIs and 46 were on once-daily dosing. Using the most stringent pH criteria, namely criteria 2, pH readings were abnormal in 30% of patients on once-daily PPIs and in 25% of patients on twice-daily dosing. The prevalence of abnormal pH readings were even higher if criteria 1 or 3 were applied.

In a patient population assessed by a specialist as having clinically suspected GERD that is not responding to PPI therapy, a substantial number of patients will have abnormal esophageal pH test results. The role of pH testing in the algorithm of GERD is evolving; however, our data suggests that an abandonment of pH testing is premature.