Retransplante de fígado: validação interna de um modelo matemático preditivo de sobrevida / Liver retransplantation: internal validation of a mathematic predictive survival model

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

30/09/2009

RESUMO

Summary: The demands for liver transplantation in various countries have greatly supplanted the offer for this vital organ. In general the survival of re-transplantation patients and of the grafts are smaller than in relation to primary transplantation ones. Therefore, it is important to determine still in pre-operative patients who have a low chance to re-transplantation survival. In previous research we developed mathematical early mortality model in re- transplanted patients. Objective: To validate the mathematical surviving model created by Linhares et al. (2006), to predicting early mortality of patients undergoing liver to re-transplant. Method: It was studied prospectively 92 patients undergoing liver re-transplant in the period between September 1999 and December 2008 in Paul Brousse hospital Villejuif France. Patient data were obtained from the computerized database service and through consultation of patient records. The following variables were collected from the receiver: age, creatinine, urgency of re-transplant, time between re-transplant and transplantation. Using the ROC curve to dichotomize derivation sample and find a cut point representing the maximum sensitivity and specificity, the value found in this cut-off was 30 (>30 e <= 30, high and low-risk respectively). With the objective to validating the mathematical model compared to the areas under the ROC curves corresponding to the two independent samples (Sample derivation and validation). 95% Confidence intervals were estimated for the ROC. By the log-rank technique the two survival curves samples were compared when dichotomized in two deciles (high and low-risk). By the same statistical method both curves samples were also compared, when they were dichotomized in tertile according to the cut point of the original model: high-risk (>32), medium risk (24-32) and low risk (<24). Results: the results of the second period have showed equal results to the first one, as regards to biological variations. Either age as the creatinine and as regards the time between the transplantation and re-transplantation and the urgency with which patients were enrolled, being comparable survival curves for each of the four variables studied between the samples of derivation and validation. When compared to the areas under the curves ROC derivation (0,733) and validation (0,741) and statistical significance was not noticed (p = 0,915), showing that the sensitivity and specificity relationship between the two curves are similar. Also similarity was noticed in survival curves of Kaplan-Meier of both samples, both at cut-off dichotomized (cut-off point = 30), for tertile distribution (<24, 24-32 and >32). Conclusion: It has been possible with this study to perform internal mathematical validation of the predictive original survival model, within six months in the liver re-transplantation at a different sample period to those used for the preparation of the initial model.

ASSUNTO(S)

transplante de fígado fatores de risco falha de tratamento validação taxa de sobrevivência gastroenterologia

ACESSO AO ARTIGO

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