Impedance-pH monitoring on medications does not reliably confirm the presence of gastroesophageal reflux disease in patients referred for antireflux surgery.

INTRODUCTION

The gold standard for the objective diagnosis of gastroesophageal reflux disease (GERD) is ambulatory-pH monitoring off medications. Increasingly, impedance-pH (MII-pH) monitoring on medications is being used to evaluate refractory symptoms. The aim of this study was to determine whether an MII-pH test on medications can reliably detect the presence of GERD.

METHODS

Patients referred for persistent reflux symptoms despite pH confirmed adequate acid suppression (DeMeester score ≤14.7) were reviewed retrospectively. All patients who originally had MII-pH testing on medications were re-evaluated with an off medication Bravo-pH study. Acid exposure results (defined by off medication Bravo) were compared to the original on medication MII-pH.

RESULTS

There were 49 patients who met study criteria (median age 51). Patients had normal acid exposure during their MII-pH test on medications (average DMS 4.35). Impedance was abnormal (normal ≤47) in 25 of the 49 patients (51%). On subsequent Bravo-pH off medications, 37 patients (75.7%) showed increased esophageal acid exposure (average DMS 36.4). Bravo-pH testing was abnormal in 84% of patients with abnormal MII testing and in 67% with normal MII testing. The sensitivity and specificity of an abnormal MII-pH on medications for increased esophageal acid exposure off medications was 56.8 and 66.7%, respectively. The positive predictive value of confirming GERD from an abnormal MII-pH on medications is 84%, while the negative predictive value is 33.3%. A receiver operating characteristic (ROC) curve was generated and the area under the curve was 0.71, indicating that MII-pH on medications is a fair test (0.7-0.8) in diagnosing pathologic GERD.

CONCLUSION

Compared to the gold standard, MII-pH on medications does not reliably confirm the presence of GERD. Excellent outcomes with antireflux surgery are dependent on the presence of GERD; thus, patients should not be offered antireflux surgery until GERD is confirmed with pH testing off medications.