Can a stool antigen test accurately find Helicobacter pylori infection in patients with chronic atrophic gastritis?
Chronic atrophic gastritis (CAG) is a condition where the stomach lining thins, making it harder to detect Helicobacter pylori infection using standard tests. The stool antigen test (SAT) is a non-invasive method that looks for H. pylori proteins in a stool sample. A 2025 prospective study found that the monoclonal SAT is accurate for detecting active H. pylori infection in patients with CAG, with high specificity and good overall agreement with reference standards 5.
What the research says
A 2025 prospective study of 287 patients with chronic atrophic gastritis evaluated the diagnostic accuracy of the monoclonal stool antigen test 5. The test showed an area under the ROC curve of 0.858, indicating good overall accuracy. Sensitivity was 75.9% and specificity was 96.1%, meaning it rarely gives false positives but may miss some infections 5. In patients at high risk for gastric cancer progression, the test performed similarly, with specificity of 96.77% and positive predictive value of 95.24% 5. Agreement with the reference standard (histology plus urea breath test) was substantial overall (κ=0.72) and even stronger in high-risk patients (κ=0.77) 5.
Other sources confirm that stool antigen tests are a standard non-invasive method for H. pylori diagnosis, though their accuracy can vary depending on the clinical setting 91011. For patients with CAG, the monoclonal SAT appears to be a reliable option, especially given its high specificity and strong agreement with invasive tests 5.
What to ask your doctor
- Is the monoclonal stool antigen test available at your clinic or lab for detecting H. pylori in my condition?
- Given my chronic atrophic gastritis, would you recommend the stool antigen test or another non-invasive test like the urea breath test?
- If the stool antigen test is negative but symptoms persist, should we consider endoscopy with biopsy for confirmation?
- How does the accuracy of the stool antigen test compare with other tests in patients with gastric atrophy?
- Should I be tested for H. pylori even if I have no symptoms, given my chronic atrophic gastritis diagnosis?
This question is drawn from common patient questions about Gastroenterology and answered using cited medical research. We do not provide individualized advice.