Comparison of daytime and nighttime supine gastroesophageal reflux by pH monitoring of individuals with clinical suspicion of gastroesophageal reflux disease

This study aims to compare pHmetric characteristics of diurnal and nocturnal supine reflux. We studied 500 consecutive individuals with clinical suspicion of gastroesophageal reflux disease (GERD) who underwent esophageal high-resolution manometry and prolonged ambulatory pH monitoring. Patients were classified with supine GERD pattern when the percentage of acid reflux time in the supine position was equal to or greater than 2.2%. Data on acid reflux in the supine position during daytime and nighttime recumbency were: (i) acid exposure time, (ii) number of reflux episodes, (iii) longest reflux episode, (iv) interval between the last meal and the supine position, (v) interval between the supine position and the first acid reflux episode, and (vi) reported symptoms. Of the 500 evaluated patients, 238 (48%) had GERD. Among these, supine pattern was observed in 134 (56%) patients, bipositional in 53 (23%), and orthostatic in 51 (21%). In patients with daytime recumbency, 112 (51% of 217) were pathological refluxers, with a mean DeMeester score of 45 +/- 26. Total acid exposure time (P = 0.8) and reported Symptom Index (P = 0.2) did not differ depending on the period, whether diurnal or nocturnal. All other pHmetric parameters were lower during daytime recumbency. In conclusion, diurnal supine reflux has similar acid exposure time and temporal correlation between symptoms and reflux episodes as nocturnal supine reflux. Other pHmetric parameters are lower for diurnal supine reflux.