pH Impedance vs. traditional pH monitoring in clinical practice: an outcome study

The addition of impedance to 24-h pH monitoring has allowed detection of weakly acidic reflux, but the extent to which pH-impedance (pH-MII) monitoring improves outcomes is unknown.

This was a prospective observational study. Patients referred for pH or pH-MII monitoring completed a standardized questionnaire on improvement in the dominant symptom, their satisfaction, and treatment at 3 and 12 months after the test during a telephone interview.

A total of 184 patients (mean age, 52 years, range, 19-82 years; 35 % with typical symptoms; and 89 % tested off therapy) completed pH (n = 92) or pH-MII monitoring (n = 92) over a period of 15 months. The two arms were similar in terms of demographic, clinical, and endoscopic variables. Ten patients in the pH-MII arm showed evidence of weakly acidic reflux disease. There was no difference in the percentage of patients in the pH and pH-MII monitoring arms who experienced improvement in their dominant symptom after 3 (58 vs. 63 %; p = 0.621) or 12 months (66 vs. 70 %; p = 0.234), and the same was true for patient satisfaction. There were also no between-group difference in the use of proton pump inhibitors (PPIs) after 3 (63 vs. 68.5 %; p = 0.437) or 12 months (47 vs. 60.5 %; p = 0.051). PPIs were prescribed more frequently after a positive test (p < 0.001) although they were used by 45.6 % of the negative patients. Only one patient underwent fundoplication.

Two-thirds of patients undergoing pH-MII monitoring experience a positive outcome, similarly to what occurs after traditional pH monitoring. Physicians often pay little attention to the test results, especially if they are negative.