Helicobacter pylori plays an important role in the genesis of peptic ulcer disease and gastric cancer. There are two basic modes for detecting this infectious agent: endoscopic and nonendoscopic testing. Nonendoscopic methods include H. pylori serum antibody tests, but these are not reliable because of a high rate of false-positive results and the fact that antibodies persist even after treatment. The urea breath test is more sensitive and specific before and after treatment. However, the test has not been widely accepted by physicians because of its lack of availability, cost to the patient and questionable reimbursement. Chey and associates conducted a multicenter trial to evaluate the performance characteristics of 13C-urea blood tests in identifying H. pylori infection, with endoscopic biopsy results used as the gold standard for comparison.
Patients who were scheduled to undergo endoscopy for gastrointestinal symptoms were recruited for the study. Biopsy specimens were obtained from the stomach for histology and rapid urease tests. Patients were then given 13C-urea, and blood samples were drawn 30 minutes after administration.
A total of 121 patients were enrolled in the study, and of these, 54 (45 percent) had H. pylori present on histology. When compared with histology results, the results of the 13C-urea blood test had a sensitivity of 89 percent, a specificity of 96 percent and accuracy of 93 percent. The results of a 13C-urea test and those of a rapid urease test performed on an endoscopically obtained sample were the same. The final definition of active infection was positive histology or rapid urease test result.
The authors conclude that the 13C-urea blood test accurately identifies H. pylori infections without the need for endoscopy. This test can provide physicians with a less expensive alternative to more invasive tests, with similar accuracy rates.