Is the Immunocromatographic Fecal Antigen Test Effective for Primary Diagnosis of Helicobacter Pylori Infection in Dyspeptic Patients?

Background The diagnosis of H. pylori infection can be performed by non-invasive and invasive methods.The identification through a fecal antigen test is a non-invasive, simple, and relatively inexpensive test. Objective To determine the diagnostic performance of fecal antigen test in the identification of H. pylori infection. Methods H. pylori antigens were identified in the stools of dyspeptic patients undergoing upper gastrointestinal endoscopy. For the identification of H. pylori antigen, we use ImmunoCard STAT! HpSA with immunochromatography technique. Histopathology plus urease test were the gold standard. Results We studied 163 patients, 51% male, mean age of 56.7± 8.5years. H. pylori infection was present in 49%. Fecal test presented: sensitivity 67.5% (CI95% 60.6-72.9); specificity 85.5% (CI95% 78.9-90.7); positive predictive value 81.8% (CI95% 73.4-88.4) and negative predictive value 73,2% (CI95% 67.5-77.6); Positive likelihood ratio was 4.7 (CI95% 2.9-7.9) and Negative Likelihood Ratio 0.4 (CI95% 0.3-0.5). The prevalence odds ratio for a positive test was 12.3 (CI95% 5.7-26.3).The index kappa between FAT and histology/urease test was 0.53 (CI95% 0.39-0.64). Conclusion Immunochromatographic FAT is less expensive than the other methods and readily accepted by the patients but its diagnostic performance does not recommend its use in the primary diagnosis, when the patient may have an active infection.