Background and Aims:Liver transplantation(LT)using ABO-incompatible(ABOi)grafts can extend the donor pool to a certain extent and hence reduce the waiting time for transplantation.However,concerns of the impending pro...Background and Aims:Liver transplantation(LT)using ABO-incompatible(ABOi)grafts can extend the donor pool to a certain extent and hence reduce the waiting time for transplantation.However,concerns of the impending prognosis associated with this option,especially for patients with liver failure and higher model for end-stage liver disease(MELD)scores,who tend to be more fragile during the waiting period before LT.Methods:Recipients undergoing LT for acute-onchronic liver failure or acute liver failure were retrospectively enrolled at four institutions.Overall survival was compared and a Cox regression analysis was performed.Propensity score matching was performed for further comparison.Patients were stratified by MELD score and cold ischemia time(CIT)to determine the subgroups with survival benefits.Results:Two hundred ten recipients who underwent ABOi LT and 1,829 who underwent ABO compatible(ABOc)LT were enrolled.The 5-year overall survival rate was significantly inferior in the ABOi group compared with the ABOc group after matching(50.6%vs.75.7%,p<0.05).For patients with MELD scores≤30,using ABOi grafts achieved a comparable overall survival rate as using ABOc grafts(p>0.05).Comparison of the survival rates revealed no statistically significant difference for patients with MELD scores≥40(p>0.05).For patients with MELD scores of 31-39,the overall survival rate was significantly inferior in the ABOi group compared with the ABOc group(p<0.001);however,the rate was increased when the liver graft CIT was<8 h.Conclusions:For recipients with MELD scores≤30,ABOi LT had a prognosis comparable to that of ABOc LT and can be regarded as a feasible option.For recipients with MELD scores≥40,ABOi should be adopted with caution in emergency cases.For recipients with MELD scores of 31-39,the ABOi LT prognosis was worse.However,those patients benefited from receiving ABOi grafts with a CIT of<8 h.展开更多
In this article, to improve the doubly robust estimator, the nonlinear regression models with missing responses are studied. Based on the covariate balancing propensity score (CBPS), estimators for the regression coef...In this article, to improve the doubly robust estimator, the nonlinear regression models with missing responses are studied. Based on the covariate balancing propensity score (CBPS), estimators for the regression coefficients and the population mean are obtained. It is proved that the proposed estimators are asymptotically normal. In simulation studies, the proposed estimators show improved performance relative to usual augmented inverse probability weighted estimators.展开更多
This paper deals with estimation and test procedures for restricted linear errors-invariables(EV) models with nonignorable missing covariates. We develop a restricted weighted corrected least squares(WCLS) estimator b...This paper deals with estimation and test procedures for restricted linear errors-invariables(EV) models with nonignorable missing covariates. We develop a restricted weighted corrected least squares(WCLS) estimator based on the propensity score, which is fitted by an exponentially tilted likelihood method. The limiting distributions of the proposed estimators are discussed when tilted parameter is known or unknown. To test the validity of the constraints,we construct two test procedures based on corrected residual sum of squares and empirical likelihood method and derive their asymptotic properties. Numerical studies are conducted to examine the finite sample performance of our proposed methods.展开更多
基金This research was partially supported by National Natural Science Funds for Distinguished Young Scholar of China,(No.81625003)Key Program,National Natural Science Foundation of China,(No.81930016,No.81570589,No.81702858)+1 种基金Youth Program of National Natural Science Foundation of Zhejiang Province(No.LQ17H160006)National S&T Major Project(No.2017ZX10203205).
文摘Background and Aims:Liver transplantation(LT)using ABO-incompatible(ABOi)grafts can extend the donor pool to a certain extent and hence reduce the waiting time for transplantation.However,concerns of the impending prognosis associated with this option,especially for patients with liver failure and higher model for end-stage liver disease(MELD)scores,who tend to be more fragile during the waiting period before LT.Methods:Recipients undergoing LT for acute-onchronic liver failure or acute liver failure were retrospectively enrolled at four institutions.Overall survival was compared and a Cox regression analysis was performed.Propensity score matching was performed for further comparison.Patients were stratified by MELD score and cold ischemia time(CIT)to determine the subgroups with survival benefits.Results:Two hundred ten recipients who underwent ABOi LT and 1,829 who underwent ABO compatible(ABOc)LT were enrolled.The 5-year overall survival rate was significantly inferior in the ABOi group compared with the ABOc group after matching(50.6%vs.75.7%,p<0.05).For patients with MELD scores≤30,using ABOi grafts achieved a comparable overall survival rate as using ABOc grafts(p>0.05).Comparison of the survival rates revealed no statistically significant difference for patients with MELD scores≥40(p>0.05).For patients with MELD scores of 31-39,the overall survival rate was significantly inferior in the ABOi group compared with the ABOc group(p<0.001);however,the rate was increased when the liver graft CIT was<8 h.Conclusions:For recipients with MELD scores≤30,ABOi LT had a prognosis comparable to that of ABOc LT and can be regarded as a feasible option.For recipients with MELD scores≥40,ABOi should be adopted with caution in emergency cases.For recipients with MELD scores of 31-39,the ABOi LT prognosis was worse.However,those patients benefited from receiving ABOi grafts with a CIT of<8 h.
文摘In this article, to improve the doubly robust estimator, the nonlinear regression models with missing responses are studied. Based on the covariate balancing propensity score (CBPS), estimators for the regression coefficients and the population mean are obtained. It is proved that the proposed estimators are asymptotically normal. In simulation studies, the proposed estimators show improved performance relative to usual augmented inverse probability weighted estimators.
基金Supported by the Zhejiang Provincial Natural Science Foundation of China(LY15A010019)National Natural Science Foundation of China(11501250)
文摘This paper deals with estimation and test procedures for restricted linear errors-invariables(EV) models with nonignorable missing covariates. We develop a restricted weighted corrected least squares(WCLS) estimator based on the propensity score, which is fitted by an exponentially tilted likelihood method. The limiting distributions of the proposed estimators are discussed when tilted parameter is known or unknown. To test the validity of the constraints,we construct two test procedures based on corrected residual sum of squares and empirical likelihood method and derive their asymptotic properties. Numerical studies are conducted to examine the finite sample performance of our proposed methods.
