Browsing by Author "Marshall Rivera, Guillermo"
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- ItemA Bayesian approach for nonlinear regression models with continuous errors(2003) Cruz Mesía, Rolando J. de la; Marshall Rivera, Guillermo
- ItemA comparison of single and combined visual, cytologic, and virologic tests as screening strategies in a region at high risk of cervical cancer(AMER ASSOC CANCER RESEARCH, 2003) Ferreccio Readi, Catterina; Bratti, María C.; Sherman, Mark E.; Herrero, Rolando; Marshall Rivera, Guillermo; Wacholder, Sholom; Hildesheim, Allan; Burk, Robert D.; Hutchinson, Martha; Alfaro, Mario; Greenberg, Mitchell D.; Morales, Jorge; Rodríguez, Ana C.; Schussler, John; Eklund, Claire; Schiffman, Mark
- ItemA new score for predicting neonatal very low birth weight mortality risk in the NEOCOSUR South American Network(NATURE PUBLISHING GROUP, 2005) Marshall Rivera, Guillermo; Tapia Illanes, José Luis; D'Apremont Ormeño, Ivonne; Grandi, C.; Barros, C.; Alegri, A.; Fabres Biggs, Jorge Guillermo; Standen, J.; Panizza, R.; Roldán, L.; Musante, G.; Bancalari, A.; Bambaren, E.; Lacarruba J.; Hubner M. E.; Decaro, M.; Maríani, G.; Kurlat, I.; González, A.
- ItemA reply to MS Kramer, Isocaloric protein supplementation during pregnancy(2000) Mardones S., Francisco; Marshall Rivera, Guillermo; Rosso R., Pedro Pablo; Uiterwaal, D,
- ItemA risk prediction model for severe intraventricular hemorrhage in very low birth weight infants and the effect of prophylactic indomethacin(2014) Luque, M.; Tapia Illanes, José Luis; Villarroel del Pino, Luis A.; Marshall Rivera, Guillermo; Musante, G.; Carlo, W.; Kattan Said, Alberto Javier
- ItemAcademic performance of medical students. A predictable result?(SOC MEDICA SANTIAGO, 2000) Bastías, Gabriel; Villarroel del Pino, Luis A.; Zúñiga Parada, Denisse Alejandra; Marshall Rivera, Guillermo; Velasco Fuentes, Nicolas; Mena Concha, Beltrán
- ItemAcute myocardial infarction mortality in comparison with lung and bladder cancer mortality in arsenic-exposed region II of Chile from 1950 to 2000(2007) Yuan, Yan; Marshall Rivera, Guillermo; Ferreccio Readi, Catterina; Steinmaus, Craig; Selvin, Steve; Liaw, Jane; Bates, Michael N.; Smith, Allan H.
- ItemAge at Exposure to Arsenic in Water and Mortality 30-40 Years After Exposure Cessation(OXFORD UNIV PRESS INC, 2018) Roh, Taehyun; Steinmaus, Craig; Marshall Rivera, Guillermo; Ferreccio Readi, Catterina; Liaw, Jane; Smith, Allan H.
- ItemAN ANALYSIS OF INTEROBSERVER RELIABILITY AND REPRESENTATIVENESS OF DATA FROM THE VETERANS AFFAIRS COOPERATIVE STUDY ON PROCESSES, STRUCTURES, AND OUTCOMES IN CARDIAC-SURGERY(LIPPINCOTT-RAVEN PUBL, 1995) Henderson, W. G.; Moritz, T. E.; Shroyer, A. L.; Johnson, R.; Marshall Rivera, Guillermo; llis, N. K.; Sethi, G. K.; Grover, F. L.; Hammermeister, K. E.
- ItemAn assessment of the severity, proportionality and risk of mortality of very low birth weight infants with fetal growth restriction. A multicenter South American analysis(2005) Grandi, Carlos; Tapia Illanes, José Luis; Marshall Rivera, Guillermo; Musante, G.; Kurlat, I.; Mariani, G.; Roldán, L.; Agost, D.; Grandi, C.; Decaro, M.; Estay Navarrete, Alberto Santiago; Ramírez, R.; Bancalari, A.; Standen, J.; González, A.; Alegria, A.; Lacarruba, J. M.; Zegarra, J.; Panizza, R.
- ItemAssessment of predictive models for binary outcomes: an empirical approach using operative death from cardiac surgery(Wiley, 1994) Marshall Rivera, Guillermo; Grover, Frederick L.; Henderson, William G.; Hammermeister, Karl E.Predictive models in medical research have gained popularity among physicians as an important tool in medical decision making. Eight methodological strategies for creating predictive models are compared in a large, complex data base consisting of preoperative risk and operative outcome data on 12,712 patients undergoing coronary artery bypass grafting and entered into the Department of Veterans Affairs Cardiac Surgery Risk Assessment Program between April 1987 and March 1990. The models under consideration were developed to predict operative death (any death within 30 days following the surgical procedure or later if the result of a perioperative complication). The two strategies with the best predictive power among the eight examined were stepwise logistic regression alone and data reduction by cluster analysis combined with clinical judgement followed by a logistic regression model. The additive model based on unadjusted relative risks, the model based on Bayes' Theorem, and the logistic model using all candidate variables were good alternatives. Whether or not we imputed values did not have a significant impact on the predictive power of the models.
- ItemBayesian-logit model for risk assessment in coronary artery bypass grafting(1994) Marshall Rivera, Guillermo; Shroyer, A. Laurie; Grover, Frederick L.; Hammermeister, Karl E.Predictive models for the assessment of operative risk using patient risk factors have gained popularity in the medical community as an important tool for the adjustment of surgical outcome. The Bayes' theorem model is among the various models used to predict mortality among patients undergoing coronary artery bypass grafting procedures. Comparative studies of the various classic statistical techniques, such as logistic regression, cluster of variables followed by a logistic regression, a subjectively created sickness score, classification trees model, and the Bayes' theorem model, have shown that the Bayes' model is among those with the highest predictive power. In this study, the Bayes' theorem model is reformulated as a logistic equation and extended to include qualitative and quantitative risk factors. We show that the resulting model, the Bayesian-logit model, is a mixture of logistic regression and linear discriminant analysis. This new model can be created easily without complex computer programs. Using 12,712 patients undergoing coronary artery bypass grafting procedures at the Department of Veterans Affairs Continuous Improvement in Cardiac Surgery Study between April 1987 and March 1990, the predictive power of the Bayesian-logit model is compared with the Bayes' theorem model, logistic regression, and discriminant analysis. The ability of the Bayesian-logit model to discriminate between operative deaths and operative survivors is comparable with that of logistic regression and discriminant analysis
- ItemBile acid synthesis is increased in Chilean Hispanics with gallstones and in gallstone high-risk Mapuche Indians(2004) Gälman, Cecilia; Miquel P., Juan Francisco; Pérez Ayuso, Rosa María; Einarsson, Curt; Stahle, Lars; Marshall Rivera, Guillermo; Nervi, Flavio; Rudling, Mats
- ItemBREASTFEEDING PATTERN AND THE DURATION OF LACTATIONAL AMENORRHEA IN URBAN CHILEAN WOMEN(1988) Díaz, S.; Rodríguez, G.; Marshall Rivera, Guillermo; Pino Manresa, Guido del; Casado, M. E.; Miranda, P.; Schiappacasse, V.; Croxatto A., Horacio
- ItemChile: Socioeconomic Differentials and Mortality in a Middle-Income Nation(OXFORD UNIVERSITY PRESS, 2009) Vega Morales, Jeanette; Hollstein, Rolf Dieter; Delgado, Iris; Pérez, Juan C.; Carrasco Zúñiga, Sebastián Andrés; Marshall Rivera, Guillermo; Yach, Derek
- ItemCHOLESTEROL LEVELS AND EARLY DIABETIC RENAL AND RETINAL DAMAGE IN SUBJECTS WITH TYPE-I DIABETES(EDITRICE KURTIS S R L, 1992) Garg, S. K.; Chase, H. P.; Marshall Rivera, Guillermo; Jackson, W. E.; Holmes, D. L.
- ItemCluster analysis using multivariate mixed effects models(WILEY, 2009) Villarroel del Pino, Luis A.; Marshall Rivera, Guillermo; Baron, Anna E.
- ItemComparación de dos métodos para corregir el sesgo de no respuesta a una encuesta: sustitución muestral y ajuste según propensión a responder(2009) Vives Vergara, Alejandra; Ferreccio Readi, Catterina; Marshall Rivera, Guillermo
- ItemComplementary effects of Mediterranean diet and moderate red wine intake on haemostatic cardiovascular risk factors(NATURE PUBLISHING GROUP, 2001) Mezzano, Diego; Leighton Puga, Federico; Martínez, Carlos; Marshall Rivera, Guillermo; Cuevas Marín, Ada Marisa; Castillo Valenzuela, Oscar; Panes Becerra, Olga Teresa; Rozowski Narkunska, Samuel Jaime; Pérez Pons, Druso Diego; Mizón Costa, Claudio Luis Enrique; San Martin, Alejandra; Pereira Pereira, J. Marcello
- ItemContinuous assessment and improvement in quality of care. A model from the Department of Veterans Affairs Cardiac Surgery(1994) Hammermeister, Karl E.; Johnson, Randall; Marshall Rivera, Guillermo; Grover, Frederick L.Objective: The authors organized the Department of Veterans Affairs (VA) Continuous Improvement in Cardiac Surgery Study (CICSS) to provide risk-adjusted outcome data for the continuous assessment and improvement of quality of care for all patients undergoing cardiac surgery in the VA. Background: The use of risk-adjusted outcomes to monitor quality of health care has the potential advantage over consensus-derived standards of being free of preconceived biases about how health care should be provided. Monitoring outcomes of all health care episodes, as opposed to review of selected cases (e.g., adverse outcomes), has the advantages of greater statistical power, the opportunity to compare processes of care between good and bad outcomes, and the positive psychology of treating all providers equally. These two concepts, together with a pre-existing peer committee (the VA Cardiac Surgery Consultants Committee) to review, interpret, and act on the risk-adjusted outcome data, form the primary design considerations for CICSS. Methods: Patient-level risk and outcome (operative mortality and morbidity) data are collected prospectively on each of the approximately 7000 patients undergoing cardiac surgery in the VA each year. These outcomes, adjusted for patient risk using logistic regression, are provided every 6 months to each cardiac surgery program and to a national peer review committee for internal and external quality assessment and improvement. Results: For the most recent 12-month period with complete data collection, observed-to-expected (O/E) ratios ranged from 0.2 to 2.2, with eight centers falling outside of the 90% confidence limits for an O/E ratio equaling 1.0. The O/E ratio for all centers has fallen by 14% over the 4.5-year period of this program (p = 0.06). Conclusions: A large-scale, low-cost program of continuous quality improvement using risk-adjusted outcome is feasible. This program has been associated with a decrease in risk-adjusted operative mortality.