Background and Aim: A cut-off value of 2.5‰ for the 13C-urea breath test (UBT) is recommended in Japanese persons, based on the result of a multicenter trial in patients prior to treatment for eradication of Helicobacter pylori. The cut-off value of 2.5‰ has also been used in the assessment of eradication after treatment. The 6–8-week evaluation after treatment is recommended in the guidelines of the Japanese Society of Gastroenterology. The present study aimed to prospectively re-assess the cut-off value of the 13C-UBT at 6 weeks after treatment by using the results obtained at 6 months as an indication of true positive or true negative H. pylori infection status.
Methods: One hundred and ninety patients who were positive for H. pylori underwent eradication treatment, and 177 patients of these patients who were assessed as having true positive or true negative H. pylori status at 6 months after treatment were evaluated in this study. Eradication was assessed by 13C-UBT, culture, and histology at 6 weeks and at 6 months after treatment, and the cut-off value of 13C-UBT at 6 weeks was re-assessed.
Results: A cut-off value of 3.5‰. at 6 weeks after treatment showed 97.2% diagnostic accuracy, while a cut-off value of 2.5‰ at 6 weeks showed 96.0% diagnostic accuracy. For a 3.5‰ cut-off value, only five patients were positive by 13C-UBT and were negative by culture and histology at 6 weeks, and three patients were true positive and two were false positive by the 13C-UBT at 6 months.
Conclusion: A cut-off value of 3.5‰ for the 13C-UBT is recommended at 6 weeks after eradication treatment in Japanese persons.