Long-term follow-up of 13C-urea breath test results after Helicobacter pylori eradication: Frequency and significance of borderline δ13CO2 values

Abstract

Background: The precise choice of cut-off point for the 13C-urea breath test to define whether it is positive or negative represents a controversial issue. Aim: To quantify the 13C-urea breath test result for several years following Helicobacter pylori eradication, and to evaluate the frequency and the significance of borderline δ13CO 2 values. Methods: Two-hundred H. pylori eradicated patients confirmed by 13C-urea breath test (100 mg of urea, citric acid), and having had repeated this test yearly up to 5 years, were studied. δ13CO2 values between 2 and 5‰ were considered as borderline results. Results: Eight H. pylori recurrences were observed during 406 patient-years of follow-up (1.97% yearly). In two of eight reinfected patients, the reinfection was preceded by a negative δ13CO2 value >2‰. Borderline δ13CO2 values were detected in 4% of the 606 urea breath tests performed, and in 25% when only patients in whom H. pylori recurrence was detected in subsequent urea breath tests were included (P < 0.05). The negative-predictive value of a post-treatment δ 13CO2 >2‰ for the diagnosis of H. pylori recurrence was 99%. Conclusions: Positive and negative urea breath test results tend to cluster outside the range between 2‰ and 5‰. Nevertheless, a borderline urea breath test δ value (e.g. very close to the selected cut-off point) should be interpreted cautiously, and the result should probably be confirmed either by repeating the urea breath test or by other diagnostic methods. On the contrary, a δ13CO2 value <2‰ very confidently confirms H. pylori eradication. © 2006 Blackwell Publishing Ltd.