Evaluation of Helicobacter pylori stool antigen test in Thai patients with upper gastrointestinal bleeding

Stool antigen test was evaluated in comparison with other diagnostic tests for the diagnosis of H. pylori infection in Thai patients presented with upper gastrointestinal bleeding.

Fifty-six patients were enrolled and fecal specimen was obtained from 34 patients. The presence of H. pylori was considered if the culture was positive or at lease two of the other diagnostic tests (urea breath test, serology, rapid urease test or histology) were positive. Stool antigen test was performed by using commercially available monoclonal enzyme immunoassay (Amplified IDEIA HpStAR, Dako, Denmark).

Of the 56patients, 35 (62.5%0) were considered H. pylori infected, while in 34patients tested by stool antigen test, 22 (64.71%) were infected. The prevalence of H. pylori infection as determined by each test is considered low (47.06% from stool antigen test; 42.50%from UBT, 65.85%from serology; 51.78%0from RUT- and 46.34% from histology). The sensitivity/specificity/accuracy (%) of stool antigen test was 69.56/100/ 79.41 compared to 73.91/100/85 of UBT 79.17/52.94/68.29 of serology, 80/95.23/85.71 of RUT and 82.61/ 100/90.24 of histology, respectively.

In summary, the results of this study reveal that the prevalence of H. pylori was relatively low in upper gastrointestinal bleeding patients. Yielding a low sensitivity and accuracy, the stool antigen test is therefore not reliable for the diagnosis of H. pylori infection in patients with upper gastrointestinal bleeding.