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.
- pH monitoring
- erosive oesophagitis
- gastro-oesophageal reflux disease
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Correction notice This article has been corrected since it published Online First. The author affiliations have been updated and a duplicated reference removed.
Contributors Study design/conception: R-IR, MRF, TW. Acquisition of data: R-IR, MRF, ET, SZ, JMD, TW. Analysis of data: R-IR, MF, ET, FW, TW. Interpretation of data: R-IR, MRF, ET, FW TW. Drafting of the manuscript: R-IR, TW. Critical revision of the manuscript: R-IR, MRF, SZ, JMD, JJ, FW, TW. Final approval of the manuscript to be published: R-IR, MRF, ET, SZ, JMD, JJ, FW, TW.
Funding This study was funded by institutional research funds from Guy's and St Thomas' Charity, SPF872 and supported by grants and catheter-free pH monitoring equipment from Given Imaging/Covidien AG, now subsidiaries of Medtronic plc. Medtronic was not involved in discussions of the study design and did not contribute to the drafting of the manuscript.
Competing interests MRF has received research and/or educational funding from Medtronic, MMS/Laborie, Sandhill Scientific/Diversatek and Reckitt Benckiser. R-IR, ET, SZ, JMD, JJ, FW, TW: None declared.
Patient consent for publication Not required.
Ethics approval This study was approved at each centre by the NHS Health Research Authority, UK (REC Ref: 09/H0802/104, 18/LO/1467), University of Nottingham and King's College Ethics committees (ClinicalTrials.gov number NCT00481949, NCT03417817). The healthy volunteer component of the study at GSTT was included in the NIHR Clinical Research Network Portfolio (CPMS ID 39211).
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information. Available on reasonable request.
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