Efficacy of Esophageal Impedance/pH Monitoring in Patients With Refractory Gastroesophageal Reflex Disease, on and off Therapy

BACKGROUND & AIMS: Intraluminal impedance monitoring has given new dimensions to the diagnosis of reflex disease. However, there is no defined algorithm for evaluating refractory reflex symptoms. We studied whether combined impedance/pH monitoring in patients on therapy can predict acid reflex in patients off therapy and whether testing should be carried out when patients are on or off therapy. METHODS: Thirty-nine adults (mean age, 50 years; 24 female) with refractory reflex symptoms were evaluated by impedance/pH monitoring while on therapy, followed by wireless pH monitoring while off therapy. Non-acid reflex events in patients on therapy were correlated with acid reflux parameters studied off therapy. In addition, the likelihood of test abnormalities on and off therapy was determined. RESULTS: In 25 of 39 patients (64%) on therapy, impedance testing was normal, with a median of 69 events (interquartile, 63.0-78.0). The percentage of time at pH <4 was within the normal range for all patients who were on therapy. The pH test results were abnormal in 28 of 39 patients (72%) when studied off therapy. Ninety-three of patients with abnormal impedance on therapy also had abnormal acid reflux off therapy. When both groups were off therapy, the patients with abnormal impedance parameters on therapy had significantly higher median (interquartile) 2-day baseline levels of esophageal acid exposure (8.7%, 6.9%-12.5%), compared with those of patients with normal impedance parameters while on therapy (6.0%, 2.8%-9.4%; P=.026). CONCLUSIONS: Abnormal impedance in patients on therapy predicts acid reflux in patients off therapy. In patients with refractory reflex, combined impedance/pH monitoring might provide the single best strategy for evaluation of reflex symptoms.