Objectives: Current nonendoscopic tests for Helicobacter pylori include antibody tests and the urea breath test. After the administration of 13C-urea, serum bicarbonate measurement can identify those infected with H. pylori. In this study, our aims were to determine the accuracy of the urea blood test, and to compare the accuracy of the urea blood test with that of rapid urease testing of gastric biopsies.
Methods: This was a multicenter trial conducted at five sites within the U.S. Patients scheduled for endoscopy were recruited. During endoscopy, biopsies were obtained from the gastric body and antrum for histology and rapid urease testing. Patients underwent the urea blood test, which required the ingestion of 125 mg of 13C-urea after endoscopy. Thirty minutes later, a 3-ml blood sample was obtained and later analyzed by mass spectrometry for 13C-bicarbonate. Performance characteristics for the urea blood test were calculated using the endoscopic biopsy tests as a gold standard.
Results: One hundred and twenty-one patients (54 infected) were enrolled. The urea blood test yielded sensitivity of 89%, specificity of 96%, positive predictive value of 94%, negative predictive value of 91%, and accuracy of 93% using histology as a gold standard. There was no difference between results obtained with the urea blood test and rapid urease testing of gastric biopsies.
Conclusions: The urea blood test accurately identified active H. pylori infection. The performance characteristics of this nonendoscopic test were similar to those of endoscopic rapid urease testing.