Appropriate cut-off value of 13C-urea breath test after eradication of Helicobacter pylori infection in Japan

Background and Aim: A cut-off value of 2.5parts per thousand for the C-13-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 2.5parts per thousand 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 C-13-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 C-13-UBT, culture, and histology at 6 weeks and at 6 months after treatment, and the cut-off value of C-13-UBT at 6 weeks was re-assessed. Results: A cut-off value of 3.5parts per thousand(.) at 6 weeks after treatment showed 97.2% diagnostic accuracy, while a cut-off value of 2.5parts per thousand at 6 weeks showed 96.0% diagnostic accuracy. For a 3.5parts per thousand cut-off value, only five patients were positive by C-13-UBT and were negative by culture and histology at 6 weeks, and three patients were true positive and two were false positive by the C-13-UBT at 6 months. Conclusion: A cut-off value of 3.5parts per thousand for the C-13-UBT is recommended at 6 weeks after eradication treatment in Japanese persons. (C) 2003 Blackwell Publishing Asia Pty Ltd.