Accuracy of C-13-urea breath test in clinical use for diagnosis of Helicobacter pylori infection

The C-13-urea breath test (UBT) is a noninvasive test for diagnosis of Heli cobacter pylori infection of gastric mucosa. The aim of this prospective st udy was to assess the accuracy of a simple UBT in clinical routine use. Methods: The study population comprised of 100 patients (49 f, 51 m) requir ing diagnostic upper CT endoscopy. One biopsy specimen was taken from the g astric anll urn, body and fundus, respectively, for standard histological e xamination and one additional, specimen from each location was transformed into transport medium for cultivation of H. pylori. After vaccination of th e culture plates the biopsies were tested for urease activity (UAT). After recovery from endoscopy the patients had to pass an one liter endexspirator y breath sample before and 15 min after drinking 200 mi orange juice, pH 3. 6, containing 75 mg of C-13-urea. (CO2)-C-13 was measured in the breath sam ples using isotope-selective nondispersive infrared spectrometry. Results: Defining gold standard groups with all biopsy tests (from antrum a nd corpus) positive or negative die (CO2)-C-13 delta over baseline (DOB) cu t-off level of UBT was set at 6.5 parts per thousand in order to best discr iminate positive from negative patients (ROC analysis). UBT was positive in 37% of all subjects. Taken UAT and histological examination together (posi tive when both tests were positive) UBT displayed a sensitivity of 92%, a s pecificity of 94%, a positive predictive value of 89%, and a negative predi ctive value of 94%. When including the results of culture sensitivity and n egative predictive value reached almost 100%. The mean of the (CO2)-C-13-DO B values from H. pylori-positive duodenal or gastric ulcer patients did not differ from controls (H, pylori-positive patients without leasions). The ( CO2)-C-13-DOB values of the ulcer group were correlated significantly with the active inflammatory component of gastritis in antrum, corpus, and fundu s. Conclusion: UBT with this setup detects H. pylori infection in clinical rou tine use with high accuracy. The increase of exhaled (CO3)-C-13 does not pr edict ulcer disease but reflects the de -gree of active inflammation of gas tric mucosa.