Diagnostic performance of biopsy-based methods for determination of Helicobacter pylori infection without a reference standard

Endoscopic biopsy-based tests are considered to be the reference method for diagnosing Helicobacter pylori infection and monitoring antibiotic treatme nt, but unbiased data on their diagnostic performance is lacking. In this s tudy we evaluated the diagnostic performance of culture, histology and rapi d urease testing of antral biopsies separately and in combination. Antral b iopsies were taken from consecutive patients undergoing upper gastrointesti nal endoscopies at a single center between January 1995 and May 1997. The b iopsies were examined for culture, histology, and CLOtest. The diagnostic p erformance, i.e., the sensitivity and specificity of the tests was estimate d with 7 non-linear equations in 7 unknowns. To determine sources of hetero geneity that may have biased the results, data were stratified for age, gen der, and whether they were taken before or after anti-Helicobacter antibiot ic treatment. During the study period 631 patients underwent 869 upper gast rointestinal endoscopies. In 122 (14%) of the antral specimens the test res ults of culture, histology and CLOtest differed. Based on the nonlinear reg ression techniques we estimated that in 347 tests (40%) H. pylori infection was present. Overall sensitivity, specificity, positive and negative predi ctive value for each test were as fellows: culture 91.4%, 96.3%, 94.2%, 94. 4%, respectively; histology 90.3%, 97.8%, 96.4%, 93.8%, respectively; CLOte st 94.9%, 96.7%, 95.0%, 96.6%, respectively. In combination, the three test s provided the definitive diagnosis, either non-infected or infected, in 86 2 out of the 869 tests. Sensitivity of gastric antral histology was 64.9% ( 95% CI: 38-86) in females who did and 84.5% (95% CI: 77-90) in females who did not have had recent antibiotic therapy to cure the infection. Approxima tely 5-10% of H. pylori infected patients, were mis-diagnosed with a single biopsy-based test taken from the gastric antrum. Only a combination of bac terial culture, histological examination and the CLOtest represents an appr opriate reference standard for research purposes to identify infected patie nts. (C) 2000 Elsevier Science Inc. All rights reserved.