Browsing by Author "VIAL, P"

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    COST-BENEFIT-ANALYSIS FOR THE USE OF HAEMOPHILUS-INFLUENZAE TYPE-B CONJUGATE VACCINE IN SANTIAGO, CHILE
    (1993) LEVINE, OS; ORTIZ, E; CONTRERAS, R; LAGOS, R; VIAL, P; MISRAJI, A; FERRECCIO, C; ESPINOZA, C; ADLERSTEIN, L; HERRERA, P; CASAR, C
    Cost-benefit analyses can be integral to the evaluation of interventions in developing countries. The authors compare the potential benefits to the Chilean Ministry of Health, in terms of treatment costs averted, by prevention of Haemophilus influenzae type b (HIB) invasive disease, with the costs of adding HIB conjugate vaccine to the diphtheria-tetanus-pertussis (DTP) immunization routinely administered to infants. In their base-case model, over a 10-year period (1991-2000), vaccination against HIB will prevent 1,229 cases of HIB invasive disease, including 713 cases of meningitis, 107 of whom would suffer severe, long-term sequelae, and between 29 and 116 deaths. Assuming a cost of US$1 for a full three-dose regimen of vaccine, the benefit/cost ratio of 1.66, with a net discounted savings of over $403,225, illustrates that HIB vaccine can be cost-beneficial. Sensitivity analyses which alter each of the variables in the analysis indicate that if the true incidence of HIB disease is twice the published rate, then three doses of vaccine remains cost-beneficial at US$3.
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    HELICOBACTER-PYLORI-ASSOCIATED GASTRODUODENAL DISEASE IN SYMPTOMATIC CHILEAN CHILDREN - DIAGNOSTIC-VALUE OF SEROLOGICAL ASSAY
    (LIPPINCOTT-RAVEN PUBL, 1995) HODGSON, MI; PANTOJA, T; LATORRE, JJ; VIAL, P; HENRIQUEZ, A; WENGER, J; PENA, Y; SIRI, MT; GUIRALDES, E
    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.