Browsing by Author "Viviani, P."
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- ItemCompleteness of Chilean information on live births: design of a diagnostic instrument relating birth weight and gestational age at birth to neonatal mortality(ELSEVIER IRELAND LTD, 2006) Mardones, F. J.; Marshall, G.; Viviani, P.; Villarroel, L.; Tapia, J. L.; Cerda, J.; Garcia Huidobro, T.; Ralph, C.; Mardones Restat, F. J.
- ItemHelicobacter pylori Gastritis in Children Is Associated With a Regulatory T-Cell Response(2008) Harris, P.R.; Wright, S.W.; Serrano, C.; Riera, F.; Duarte, I.; Torres, J.; Peña, A.; Rollán, A.; Viviani, P.; Guiraldes, E.; Schmitz, J.M.; Lorenz, R.G.; Novak, L.; Smythies, L.E.; Smith, P.D.
- ItemIncidence and prevalence of hepatitis C virus infection in Chile.(2005) González, R.; Soza, A.; Hernández, V.; Pérez, R.M.; Alvarez, M.; Morales, A.; Arellano, M.; Riquelme, A.; Viviani, P.; Covarrubias, C.; Arrese, M.; Miquel, J.F.; Nervi, F.
- ItemRelevance of adjusted cut-off values in commercial serological immunoassays for Helicobacter pylori infection in children(2005) Harris, Paul R.; Perez-Perez, G.; Zylberberg, A.; Rollán, A.; Serrano, C.; Riera, F.; Einisman, H.; García, D.; Viviani, P.We assessed the sensitivity and specificity of H. pylori IgG and IgA with a commercial immunoassay performed in Chile and a second non-commercial immunoassay performed in a reference laboratory in the United States, in serum of 80 children and adults referred for gastrointestinal endoscopies in a developing country. Overall, 56% of the patients were infected with H. pylori based on rapid urease test and staining techniques on gastric biopsies. When Receiver Operator Curves (ROC) were developed, the sensitivity and specificity were similar for IgG and IgA. Both immunoassays exhibited better specificity, positive and negative predictive value (NPV) in children than in adults when cut-off values were corrected according to the local population than when they were assessed using the cut-off values pre-defined in other populations. These results underline the need to establish more precise cut-off values corrected in the local populations where assessments of antibodies as diagnostic markers of H. pylori infection are planning. © 2005 Springer Science+Business Media, Inc.