Characterisation of patients with supine nighttime reflux: observations made with prolonged wireless oesophageal pH monitoring.

BACKGROUND: Although nighttime reflux symptoms are common, the presence of nocturnal reflux is seldom confirmed with a standard 24 hours pH study. AIM: To study patients with supine nighttime reflux symptoms using prolonged wireless pH monitoring. METHODS: In this retrospective study, patients with typical acid reflux symptoms were studied using 96-h pH monitoring. Patients with nighttime reflux symptoms were compared to those without. Night-to-night variability and diagnostic accuracy of 24-, 48- and 72-hours pH studies compared to the 96-hours "gold standard" were evaluated. RESULTS: Of the 105 included patients (61.9% females; mean age 46.8 ± 14.4 years), 86 (81.9%) reported nighttime reflux symptoms, of which 67.4% had pathological supine nocturnal acid exposure in at least one night. There was high variance in night-to-night acid exposure (94% [IQR0-144]), which was larger than the variance in upright acid exposure (58% [IQR32-88]; P < 0.001). When analysing the first 24 hours of the pH study, 32% of patients were diagnosed with pathological supine nighttime acid exposure versus 51% of patients based upon the 96-hours pH-test. The diagnostic accuracy and yield improved with study duration (P < 0.001). Reflux episodes with a lower nadir pH or longer acid clearance time were more prone to provoke nightly symptoms. CONCLUSIONS: The majority of patients with nocturnal reflux symptoms had pathological acid exposure in at least one night of the prolonged pH recording. A high night-to-night variability in acid exposure reduces the clinical value and diagnostic yield of pH monitoring limited to 24 hours. Prolonged testing is a more appropriate diagnostic tool for patients with nocturnal reflux symptoms.

Validation of the Lyon classification for GORD diagnosis: acid exposure time assessed by prolonged wireless pH monitoring in healthy controls and patients with erosive oesophagitis.

OBJECTIVE: Acid exposure time (AET) from ambulatory pH studies and reflux oesophagitis are independent measurements used by the Lyon classification to diagnose GORD. This study aimed to validate AET reference ranges and diagnostic thresholds by analysis of 96-hour wireless pH studies from healthy, asymptomatic controls (HCs) and patients with and without oesophagitis. DESIGN: HC and consecutive patients referred for wireless pH studies (off acid suppressants for >7 days) underwent 96-hour pH studies at two tertiary referral centres. Erosive oesophagitis was categorised by the Los Angeles (LA) classification. Linear regression and receiver operating curve (ROC) analysis were performed to define optimal diagnostic cut-offs. RESULTS: Prolonged, 96-hour pH studies were completed in 39 HCs (age 28 (18-53) years, 72% female) and 944 patients (age 46 (16-85) years, 65% female), of whom 136 (14.5%) had reflux oesophagitis. Median AET in HC was 1.3% (upper 95th percentile 4.6%) for any study day and 2.6% (upper 95th percentile 6.9%) for the worst day (24-hour period) during the study. ROC analysis for average AET differentiated HC from patients with moderate-to-severe oesophagitis (LA BCD; sensitivity 87%, specificity 95%, positive predictive value (PPV) 59%, negative predictive value 99% for a cut-off AET of 4.3%; area under the receiver operating curve 0.95). Specificity was higher, but PPV was substantially lower for severe oesophagitis (LA CD). 'Worst-day' analysis provided similar results; however, day-to-day variability was high. CONCLUSION: Diagnostic thresholds for average AET were identified that accurately discriminate between HCs and patients with erosive oesophagitis. The findings provide conditional support for diagnostic criteria for GORD proposed by the Lyon Consensus.