Noninvasive detection of Helicobacter pylori infection in clinical practice: The ¹³C urea breath test

Objectives: To validate the ¹³C urea breath test for the detection of Helicobacter pylori infection both before and after treatment. Methods: ¹³C urea breath tests with 125-mg and 250-mg doses were carried out on each of 60 infected and 60 noninfected subjects. Results were compared with histological examination of gastric biopsies to establish detection limits. The best cut-off point was used in a clinical trial of the efficacy of the breath test in duodenal ulcer patients before and after antimicrobial therapy. The incremental increase (percentage, δ over baseline in U of δ/mil) in respiratory ¹³CO₂ abundance was associated with histological evidence of H.pylori. Outpatient, tertiary care medical center, and secondary and primary care facilities were included. One hundred twenty healthy asymptomatic subjects and 465 patients with duodenal ulcer disease were studied. The test kit assessed repeatability of breath sample collection and storage and stability of stored samples. Test performance was analyzed by comparison of 125-mg and 250-mg C urea with measurements at 30 and 40 min postdose. The test was used to diagnose active H. pylori infection and gauge success of antimicrobial therapy. Results: The test kit results were highly reproducible. The cut-off values were higher with 250-mg compared with 125-mg doses of ¹³C urea and 40 min compared with 30 min. Using a 125-mg ¹³C urea and test detection limit of 2.4% at 30 min, the accuracy was 94.8 (95% confidence interval = 92-97%) before antimicrobial therapy and 95.4% (95% confidence interval = 91-98%) after. An increase of 2.4% in the abundance of breath ¹³CO₂ measured 30 min after a 125-mg dose of ¹³C urea reliably indicated the presence of active H. pylori infection either before or after antimicrobial therapy. The ¹³C urea breath test provides a simple and reliable and noninvasive method of assessing H. pylori status.