Accuracy of seven different tests for the diagnosis of Helicobacter pylori infection and the impact of H2-receptor antagonists on test results

Background: In this study we compared the accuracy of seven diagnostic tests in diagnosing: Helicobacter pylori infection. Methods: Over 1 year 351 consecutive dyspeptic patients were tested for H. pylori infection by means of antral biopsy specimens for the rapid urease test (RUT), culture, microscopy (acridine stain); and the laboratory urease test (LUT) and, in addition, with C-14 urea breath test (UBT), IgG serology, and IgA serology (Orion Diagnostica Pyloriset New EIA-G and New EIA-A). The criterion for H. pylori infection was a minimum of three positive tests. Before being tested, 38% of the patients had used an H-2-receptor antagonist (H(2)RA). Results: Two-hundred and twenty-four patients (64%) were H. pylori-positive. The sensitivity and specificity of the tests were as follows (percentages): RUT, 85, 99; culture, 93, 100; microscopy, 81, 98; LUT, 80, 100; UBT, 93, 95; IgG serology, 99, 91; and IgA serology, 88, 91. The accuracy of the RUT and LUT was reduced in patients receiving H(2)RA therapy (P = 0.04 and 0.01, respectively). Conclusions: Culture, UBT, and IgG serology were all superior to the other four tests in diagnosing H. pylori infection. invasive urease-based tests were less accurate in patients receiving H2RAs.