The Role of Serological Tests in Diagnosis of Helicobacter pylori Infection in Children

Abstract

Background: Helicobacter pylori infection is a common infection that affects human beings. This infection also affects children. Different diagnostic methods such as serology, stool antigen detection, rapid urease test and histology are used to detect this microorganism. Objectives: The aim of this study was to determine the correlation between serology and histology/rapid urease test. Patients and Methods: In this study, two groups (case and control) were selected and matched for age and sex. The case group comprised of 77 children with confirmed H. pylori infection, as they had positive rapid urease test and histology results. The control group included 77 healthy children. Both case and control groups were checked serologically for detection of anti H. pylori IgM, IgG and IgA antibody titers. Receiver operating characteristic (ROC)-analysis software was used for data analysis. Results: Amongst the case group 54.6% were female and 45.4% were male. The most common complaints were abdominal pain (96%) and anorexia (82%). Using ROC-analysis method three cut-off points for IgG, IgM and IgA were obtained. These points were 3.3 U/ML for IgA, 6.4 U/ML for IgM and 9.9 U/ML for IgG. Considering cut-off points for each antibody, higher levels were considered as positive and lower levels as negative. Antibody titers were compared with gold standard methods including histologic and rapid urease tests. IgA level had a sensitivity of 64%, specificity of 58%, accuracy of 59.3%, positive predictive value of 31.5% and negative predictive value of 76.9%. IgM level had a sensitivity of 76%, specificity of 36.1%, accuracy of 74.2%, positive predictive value of 31.5% and negative predictive value of 76.9%. IgG level had a sensitivity of 58.6%, specificity of 61.3%, accuracy of 60.6%, positive predictive value of 36.9% and negative predictive value of 79.3%. Conclusions: Therefore, these antibodies have a relatively high negative predictive value and a low positive predictive value. Thus, their negative results are more valuable. The most sensitive antibody is IgM and most specific antibody is IgG. However, the performances of all serological tests for H. pylori are poor in children and these tests should not be used for diagnosis of H. pylori infection and treatment decisions for the pediatric age group.