PRECISION OF HELICOBACTER PYLORI SEROLOGY IN COMPARISON TO STOOL ANTIGEN TEST

Background and Aim:Helicobacter pylori is a bacterium allied with peptic ulcer disease, gastric adenocarcinoma, and chronic gastritis. In Iran estimated prevalence varies in different parts and with various modalities used. The clinical efficacy of noninvasive diagnostic tests varies with the age of the population studied. Immunoglobulin A (IgA) and IgG serologic tests are considered less reliable in children than adults, while other researchers supported the use of IgM. Thus, to implement diagnostic or control strategies accuracy in diagnostic tools is mandatory. We aimed to compare the efficacy of serology over stool antigen detection for H. pylori.Methods:This study was carried out in the diagnostic laboratory of the University teaching hospital, Tabriz September 2016 to December 2017. Helicobacter pylori-specific ELISA for the presence of IgG, IgA, and IgM antibodies was done on the sera of 350 cases. H. pylori stool antigen test was performed by ELISA on fresh stool obtained from each case. Using Stool antigen test as the gold standard, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated with 95% confidence intervals for IgG, IgA, and IgM.Results:IgG demonstrated the highest sensitivity (50.5%) and was significantly more specific in children than adults. Overall, IgM demonstrated low sensitivity (36.0%) in comparison to IgG but with no statistical difference between children and adults. IgA sensitivity (17.7%) was unacceptably low. IgG correlated better with stool antigen test than IgA or IgM.Conclusion:The results obtained suggest to use different cutoff values by age.

کلیدواژه ها:

H.pylori ، Serology ، Stool-antigen test ، Diagnosis