HELICOBACTER-PYLORI-ASSOCIATED GASTRODUODENAL DISEASE IN SYMPTOMATIC CHILEAN CHILDREN - DIAGNOSTIC-VALUE OF SEROLOGICAL ASSAY

A newly developed enzyme-linked immunosorbent assay (ELISA) IgG serolo gical assay for the diagnosis of Helicobacter pylori infection was use d recently in two epidemiological surveys in Chile. To evaluate the di agnostic efficacy of this assay in a local symptomatic pediatric popul ation, we studied 70 school-age patients referred for upper gastrointe stinal endoscopy because of complaints suggestive of gastroduodenal di sease. Evidence for antral H. pylori infection was sought by three bio psy-related methods: culture, histology, and urease activity. IgG anti -H. pylori serum antibodies were deter mined by ELISA. Altogether, chr onic antral gastritis was found in 55 patients and duodenal ulcers in nine; 11 subjects had normal histology. Sixty (86%) patients had H. py lori in the antrum. This group had significantly higher mean IgG optic al density values when compared with the H. pylori-negative group (1.8 60 versus 0.669; p < 0.001). The sensitivity and specificity of the as say in detecting antral H. pylori were both 90%; the positive predicti ve value was 98% and the negative, 60%. Accuracy of the assay was supe rior in predicting the presence or absence of gastroduodenal lesions w ith a sensitivity of 96%, a specificity of 92%, a positive predictive value of 98%, and a negative predictive value of 86%. We conclude that the diagnostic efficiency of this assay renders it appropriate both t o screen for H. pylori-associated gastroduodenal disease in individual patients and to be used in seroepidemiological surveys.