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

A newly developed enzyme-linked immunosorbent assay (ELISA) IgG serological assay for the diagnosis of Helicobacter pylori infection was used recently in two epidemiological surveys in Chile. To evaluate the diagnostic efficacy of this assay in a local symptomatic pediatric population, we studied 70 school-age patients referred for upper gastrointestinal endoscopy because of complaints suggestive of gastroduodenal disease. Evidence for antral H. pylori infection was sought by three biopsy-related methods: culture, histology, and urease activity. IgG anti-H. pylori serum antibodies were deter mined by ELISA. Altogether, chronic antral gastritis was found in 55 patients and duodenal ulcers in nine; 11 subjects had normal histology. Sixty (86%) patients had H. pylori in the antrum. This group had significantly higher mean IgG optical density values when compared with the H. pylori-negative group (1.860 versus 0.669; p < 0.001). The sensitivity and specificity of the assay in detecting antral H. pylori were both 90%; the positive predictive value was 98% and the negative, 60%. Accuracy of the assay was superior in predicting the presence or absence of gastroduodenal lesions with 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 to screen for H. pylori-associated gastroduodenal disease in individual patients and to be used in seroepidemiological surveys.