Urea Breath Test - Comparing 2 Points to 4 Points Test
Shi Yan LEE1, Jonathan Wei Jie LEE1,2, Kewin SIAH1, Phyllis CHIN3, Jiawen DAI3, Calvin Jianyi KOH1,2
Affliations:
1Department of Gastroenterology and Hepatology, National University Hospital, Singapore
2Yong Loo Lin School of Medicine, National University Singapore
3National University Singapore Gastro Motility Lab, National University Hospital, Singapore
Corresponding email address:
Shi Yan LEE (shi_yan_lee@nuhs.edu.sg)
Aim: To determine which 2 points of the 13C-urea breath test (13C-UBT) are able to maintain high diagnostic accuracy for H pylori infection – with the ultimate goal of optimizing cost efficiency.
Methods: A retrospective analysis of 1533 patients who underwent the13C-UBT between September 2019 to December 2020 in the National University Hospital, Singapore was conducted. A baseline breath test was first measured. Patients were then given 100 mg of 13C-urea dissolved in 125 mL of water mixed with citric acid, and 3 post-urea breath samples were obtained at 10 minutes’ intervals (T0, T10, T20, T30). A positive result for H pylori infection was recorded when the delta-over-baseline (DOB) value was over 4.0 at any one point of the 3 readings obtained at T10, T20, T30. Results were analysed using the Chi square test and the McNemar test.
Results: A total of 282 (18.4%) patients tested overall positive forH pylori infection. 266 out of 282 (94.3%) patients tested positive by T10. The sensitivity of the test increased to 97.5% for a 3-points test at T0-T10-T20 and 99.3% T0-T10-T30. When comparing a 2-points test at T0-T10 with a 3-points test at T0-T10-T30, 5.0% of positive cases were missed (p value < 0.001).
Conclusion: A 2-points 13C-UBT at T0-T10, using a DOB cut-off value of 4.0, retains 94.3% sensitivity of the test. Furthermore, a 3-points test (omitting one breath at 20 minutes) achieves a high diagnostic accuracy (99.3%) as both early and delayed responders are picked up by this method. Future analysis can be carried out by comparing different DOB values at each time points to increase the sensitivity of 13C-UBT, with an external gold standard (e.g. biopsy) as confirmation.