Methodological validation and clinical usefulness of carbon-14-urea breath test for documentation of presence and eradication of Helicobacter pylori

A simple [14C]urea breath test (C-14-UBT) was validated with aims of determining accuracy in documenting both the presence and proof of eradication of Helicobacter pylori infection. Fifty-six dyspeptic patients had endoscopy with biopsies and C-14-UBT. Eleven biopsy-proven H. pylori-negative patients allowed C-14-UBT normal value determination. Forty-three patients with recurrent peptic ulcer disease and biopsy-proven H. pylori infection were included in an antimicrobial eradication protocol. Endoscopy with biopsies and C-14-UBT were done again 8 wk after initiation of treatment in 35 patients. For C-14-UBT, 185 kBq (5 microCi) of [14C]urea was swallowed. Breath samples obtained up to 20 min were counted to calculate AS20, [(% 14CO2 dose excreted/mmol of CO2) x kg] at 20 min. Combined histologic and microbiologic analyses of antral biopsies were used as a gold standard. The positivity value was set as AS20 > 0.33% (mean + 3 s.d. of AS20 in H. pylori-negative patients). Diagnosis of H. pylori infection was correct with C-14-UBT in 55/56 patients (44 true-positive, 11 true-negative and 1 false-negative; sensitivity = 98%; specificity = 100%). As a proof of eradication, C-14-UBT correctly classified 33/35 patients (5 true-positive, 28 true-negative and 2 false-positive; sensitivity = 100%; specificity = 93%). The C-14-UBT global performance yielded sensitivity, specificity and accuracy of 98%, 95% and 97%, respectively. A significant correlation (r = 0.84) was found between AS20 and the number of H. pylori colonies on culture. This C-14-UBT is highly accurate both for diagnosis and proof of eradication of H. pylori infection and reflects the antral bacterial load. It is simple, fast and inexpensive, and it is therefore suitable for clinical practice.