Background The sensitivity of 24-h pH monitoring is poor in non-erosive reflux disease (NERD). In NERD patients, the proximal extent of acid reflux is one of the main determinants of reflux perception. The present study was aimed to compare the diagnostic accuracy of acid exposure time (AET), at 5 cm above the lower esophageal sphincter, with those at 10 cm and at 3 cm below the upper esophageal sphincter as well as the reproducibility of these parameters.
Methods A total of 93 consecutive NERD patients, with typical symptoms responsive to proton pump inhibitor treatment, and 40 controls underwent esophageal manometry and multi-channel 24-h pH-test; 13 patients underwent the same study on two occasions. Symptom association probability (SAP) values were evaluated at each esophageal level.
Key Results The ROC curve indicates that the area under the curve was 0.79 at distal (SE = 0.039), 0.87 (SE = 0.032) at proximal (P = 0.029 vs distal), and 0.85 (SE = 0.033) at very proximal esophagus (P = 0.148). AET showed a reproducibility of 61% (Kappa 0.22) at distal esophagus, 77% (Kappa 0.45) at proximal and 53% (Kappa 0.05) at very proximal esophagus. The percentage of patients with a positive SAP was not significantly different when assessed at the distal compared with the proximal esophagus.
Conclusions & Inferences In NERD patients, the diagnostic yield of the pH test is significantly improved by the assessment of AET at the proximal esophagus. As this variable seems to be less affected by the day to day variability, it could be considered a reliable and useful diagnostic tool in NERD patients.