Background & aims: Extending an ambulatory pH study by using a wireless capsule system could improve diagnosis of gastroesophageal reflux disease in patients with symptoms potentially related to acid reflux events. We determined the relative value of a 2-day versus a 1-day study in detection of abnormal esophageal acid exposure and reflux symptom associations.
Methods: Subjects who had undergone pH monitoring with the wireless system for symptom evaluation and who had at least 1 typical or atypical symptom during monitoring were studied (n = 157). Acid exposure time, symptom index, and a measure of reflux-associated symptom probability were calculated after 1 day of recording and compared to final results from analysis of 2 days of data.
Results: Extending recording time increased the number of subjects recording symptoms by 6.8% and doubled the number of symptoms available for association with acid reflux events. Other advantages were greater in subjects off antireflux therapy, wherein lengthening recording time increased the proportion of subjects with abnormal acid exposure time by 12.4% and significantly increased the likelihood of a positive reflux symptom relationship in subjects with atypical symptoms. Accuracy of a 1-day study ranged from 0.87-0.88 for acid exposure time to as low as 0.72-0.87 for the probability test, the most sensitive of the symptom association tests.
Conclusions: Extending recording time to 2 days with the wireless pH monitoring system increases the likelihood of detecting reflux disease in patients undergoing symptom evaluation. Benefits are most evident for subjects with atypical symptoms and for establishing reflux symptom associations by probability testing.