Comparison of distribution of intraesophageal pH during nighttime recumbency among patients with gastroesophageal reflux disease.

Background: Nighttime reflux has been demonstrated to be associated with a more aggressive presentation of gastroesophageal reflux disease (GERD). However, it has remained unknown until now if the difference in nighttime reflux between the different GERD groups is related to the distribution of intraesophageal pH level or duration of acid exposure.

Aim: To compare distribution of intraesophageal pH during nighttime between patients with erosive esophagitis (EE) versus those with nonerosive reflux disease (NERD).

Methods: Patients with heartburn symptoms at least 3 times per week were included in this study. Patients were not receiving any antireflux treatment. All patients underwent an upper endoscopy to determine if esophageal inflammation was present or absent. Subsequently, patients underwent ambulatory 24-hour esophageal pH monitoring. Only those with NERD and EE were included in this study. Nighttime period was defined as the time from the moment patients entered the bed to fall asleep and until they woke up the next morning. Distribution of intraesophageal pH during nighttime was generated using a special computer program that analyzed all registered pH measurements.

Results: Nineteen patients were found to have NERD and 31 EE. Time in bed was not different between the 2 groups. The mean number of acid reflux events, mean reflux time pH<4, and mean % total time pH<4 during nighttime were significantly lower in the NERD group as compared with the EE group (13.05±4.6, 19.7±7.09, 3.6±1.2% vs. 25.44±4.4, 29.3±7.97, 5.3±1.5%, respectively, all P<0.05). Symptom index for EE was 43.8% versus 21% for NERD, P<0.05. Overall, the distribution of intraesophageal pH during nighttime was similar between NERD and EE patients for all pH ranges.

Conclusions: Patients with EE demonstrated a significantly higher nighttime esophageal acid exposure as compared with NERD, but the overall distribution of the acid exposure was similar between the 2 groups. This suggests that duration rather than intensity of nighttime intraesophageal acid exposure accounts for the difference between EE and NERD.