Infants differ from teenagers: use of non-invasive tests for detection of Helicobacter pylori infection in children

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Abstract
All diagnostic tests for detection of Helicobacter pylori infection in adults are generally feasible for children, but they need to be validated properly in all age groups. Most non-invasive tests have a lower accuracy in infants, toddlers and pre-school children than in school-aged children and adolescents. The sensitivity of the 13C-urea breath test is excellent in all age groups, but false positive results may occur in young children. This can be corrected for by normalizing results for individual CO2 production rates. Tests for detection of H. pylori -specific antibodies in serum, whole blood, saliva or urine tend to have a low sensitivity in young children and are not reliable in this age group. Tests for detection of H. pylori antigen in stool using polyclonal or monoclonal antibodies show a good performance independent of the child’s age. Tests validated in children in industrialised countries may not have the same accuracy in developing countries where children suffer from malnutrition and/or frequent intestinal infections. Reliable non-invasive tests that are feasible in early childhood are essential to the study of transmission of Helicobacter pylori , since most individuals get infected during the first years of life. New tests are validated by comparison with a ‘gold standard’, but no single test for detection of H. pylori infection can be used as a fully reliable reference method. Therefore, concordant results of at least two biopsy-based tests (histology, culture, rapid urease test) are considered as the ‘gold standard’. Most of the validation studies in children included only a few infants and toddlers, with low numbers particularly for H. pylori -infected individuals. Only when increasing numbers of patients were tested and separated into subgroups by age it became apparent that the accuracy of most tests is lower in young children if the same cut-off values are used as established for older children or adults. Therefore, statements such as ‘a test has been validated with good results in children’ must be interpreted with caution, unless different age groups are considered with sufficient numbers of infected and non-infected children in each age group.