Streamlining 24-hour pH study for GERD: Use of a 3-hour postprandial test

At present, the ambulatory 24-hr pH test has been used as a diagnostic tool to assess gastroesophageal reflux disease (GERD) in those patients with reflux symptoms and a normal endoscopy. However, patients poorly tolerate the prolonged nature of the 24-hr test. The aim of this study was to determine whether analyzing a 3-hr postprandial period from a full 24-hr study would be as sensitive as the longer test. Data were analyzed from a standard ambulatory 24-hr pH recording. A positive test was determined if the pH was < 4 for more than 4% of the study period with the probe placed 5 cm above the lower esophageal sphincter for both groups. The data were then reanalyzed by determining the percent time of pH < 4 during a 3-hr postprandial period. The results of 50 patients with a positive 24-hr test were compared with 50 patients with normal tests. The meal that was used to study the 3-hr postprandial period occurred in the late afternoon or early evening. The 3-hr postprandial test had a sensitivity of 88% when compared to the 24-hour test and a specificity of 98%. The positive predictive value was 100% for the 3-hr test, and the accuracy of this shorter test when compared with the standard 24-hour test was 95%. In conclusion the 3-hr postprandial analysis is a highly sensitive and specific test for demonstrating GERD. By using the shorter test, patient discomfort may be reduced and compliance enhanced.