Introduction: Prolonged, 4-day (96 h) measurement by the wireless Bravo system provides an opportunity to assess the variance, diagnostic reproducibility, and yield of 24- and 48-h pH and symptom association studies.
Method: Retrospective analysis of 83 patients with suspected reflux symptoms undergoing wireless pH monitoring with the intention of 96-h measurement. Study periods were classified based on esophageal acid exposure, the DeMeester score (DMS), and the association of reflux events and symptoms (symptom index). The technical success of prolonged pH recording and diagnostic accuracy of 24-, 48-, and 72-h pH studies compared to the 96-h "gold standard" were assessed.
Results: Prolonged Bravo pH studies were possible and well tolerated in routine clinical practice. Complete 96-h recordings were available for 34/83 (41%) patients. Variation in pH measurements reduced with increasing study duration (24-h 45%vs 48-h 27%, P<0.01), but no change in reflux severity over time was observed (ANOVA, P=ns). Abnormal acid exposure was found in 7 (19%) on every test day and 21 (58%) on at least one of four test days. A diagnosis consistent with the 96-h "gold standard" was present in 22 (63%), 29 (83%), and 32 (91%) patients for 24-, 48-, and 72-h test periods, respectively, with a significant improvement of diagnostic sensitivity with study duration (P<0.01). Similar findings were present for symptom association.
Conclusion: Increasing the duration of pH studies progressively improves measurement variance and the diagnostic reproducibility of reflux studies. Future studies must address the impact of prolonged pH studies on clinical management.