Determinants of Abnormal Supine Reflux in 24-Hour pH Recordings

A previous study showed that supine gastroesophageal reflux occurs mainly in the early nighttime period and is greater if the patient retires within 2 hr of a meal. We analyzed 306 consecutive esophageal pH studies between January and July 2003. Ninety-two patients had abnormal supine reflux. The recumbent period was divided into quarters (Q1-Q4) and reflux parameters were calculated for each period. Reflux was maximal in Q1, and decreased progressively from Q1 to Q4 (P<0.001). Median time between evening meal and retiring was no different from that for 44 upright gastroesophageal reflux patients. Patients retiring within 2 hr of a meal had a higher percentage supine reflux time (P=0.012), but no increase in reflux was observed in those retiring within 3 hr. Supine reflux occurs maximally in the early nighttime period. Although not fully explained as a postprandial phenomenon, these patients should avoid going to bed within 3 hr of a meal.