目的基于二维斑点追踪成像(STI)技术探讨中重度二尖瓣反流(MR)术后左心室三维射血分数(Heart Model EF)降低的潜在预测因子。方法选取2017年1月—2018年7月拟行手术的中重度MR病人52例,按照术后1年左心室Heart Model EF比术前降低程度...目的基于二维斑点追踪成像(STI)技术探讨中重度二尖瓣反流(MR)术后左心室三维射血分数(Heart Model EF)降低的潜在预测因子。方法选取2017年1月—2018年7月拟行手术的中重度MR病人52例,按照术后1年左心室Heart Model EF比术前降低程度的不同分为A组31例(收缩功能正常或降低程度≤10%)、B组21例(降低程度>10%)。选取30名健康志愿者作为对照组。比较3组病人的常规超声心动图参数以及左室心肌纵向应变参数,并分析术后1年Heart Model EF降低的预测因子。结果术前,A组左室收缩期整体纵向应变(GLS)、左室心尖部收缩期纵向峰值应变(Apex-LS)、左室心尖段收缩期纵向峰值应变(ALS)、左室前壁收缩期纵向峰值应变(A-LS)及左室前侧壁收缩期纵向峰值应变(AL-LS)的绝对值均小于对照组(P<0.05),B组全部超声左室心肌纵向应变参数的绝对值均小于对照组,差异均有统计学意义(P<0.05);随着术后时间的增加,A组和B组超声左室心肌纵向应变各项参数逐渐升高,直到术后1年,A组各项参数基本恢复正常,但B组明显低于A组,差异均有统计学意义(P<0.05)。单因素Logistic回归分析提示,GLS、左室基底段收缩期纵向峰值应变(BLS)及左室下壁收缩期纵向峰值应变(I-LS)为术后Heart Model EF降低的影响因素(P<0.05),GLS、BLS及I-LS曲线下面积分别为0.693、0.817及0.702,临界值分别为-18.26%、-18.93%、-18.37%,敏感度分别为68%、79%及66%,特异性分别为93%、78%及91%。进一步多因素Logistic回归分析,提示仅有BLS用于预测中重度MR术后三维射血分数降低有统计学意义(P<0.05)。结论STI可为中重度MR病人在选择手术时机时提供可靠参考依据,左室GLS、BLS及I-LS均可用作中重度MR术后三维射血分数降低的预测因子,其中BLS临床价值更大。展开更多
Modeling the mean and covariance simultaneously is a common strategy to efficiently estimate the mean parameters when applying generalized estimating equation techniques to longitudinal data. In this article, using ge...Modeling the mean and covariance simultaneously is a common strategy to efficiently estimate the mean parameters when applying generalized estimating equation techniques to longitudinal data. In this article, using generalized estimation equation techniques, we propose a new kind of regression models for parameterizing covariance structures. Using a novel Cholesky factor, the entries in this decomposition have moving average and log innovation interpretation and are modeled as the regression coefficients in both the mean and the linear functions of covariates. The resulting estimators for eovarianee are shown to be consistent and asymptotically normally distributed. Simulation studies and a real data analysis show that the proposed approach yields highly efficient estimators for the parameters in the mean, and provides parsimonious estimation for the covariance structure.展开更多
This paper considers large sample inference for the regression parameter in a partially linear regression model with longitudinal data and a-mixing errors. The authors introduce an estimated empirical likelihood for t...This paper considers large sample inference for the regression parameter in a partially linear regression model with longitudinal data and a-mixing errors. The authors introduce an estimated empirical likelihood for the regression parameter and show that its limiting distribution is a mixture of central chi-squared distributions. Also, the authors derive an adjusted empirical likelihood method which is shown to have a central chi-square limiting distribution. A simulation study is carried out to assess the performance of the empirical likelihood method.展开更多
基金Projects(52102405,71901223)supported by the National Natural Science Foundation of ChinaProjects(2021JJ40746,2021JJ40603)supported by the Natural Science Foundation of Hunan Province,China+2 种基金Project(kfj220701)supported by the Open Fund of Hunan Key Laboratory of Smart Roadway and Cooperative Vehicle-Infrastructure Systems(Changsha University of Science and Technology),ChinaProject(21B0335)supported by the Scientific Research Program of the Education Department of Hunan Province,ChinaProject(2023M731962)supported by the China Postdoctoral Science Foundation。
文摘目的基于二维斑点追踪成像(STI)技术探讨中重度二尖瓣反流(MR)术后左心室三维射血分数(Heart Model EF)降低的潜在预测因子。方法选取2017年1月—2018年7月拟行手术的中重度MR病人52例,按照术后1年左心室Heart Model EF比术前降低程度的不同分为A组31例(收缩功能正常或降低程度≤10%)、B组21例(降低程度>10%)。选取30名健康志愿者作为对照组。比较3组病人的常规超声心动图参数以及左室心肌纵向应变参数,并分析术后1年Heart Model EF降低的预测因子。结果术前,A组左室收缩期整体纵向应变(GLS)、左室心尖部收缩期纵向峰值应变(Apex-LS)、左室心尖段收缩期纵向峰值应变(ALS)、左室前壁收缩期纵向峰值应变(A-LS)及左室前侧壁收缩期纵向峰值应变(AL-LS)的绝对值均小于对照组(P<0.05),B组全部超声左室心肌纵向应变参数的绝对值均小于对照组,差异均有统计学意义(P<0.05);随着术后时间的增加,A组和B组超声左室心肌纵向应变各项参数逐渐升高,直到术后1年,A组各项参数基本恢复正常,但B组明显低于A组,差异均有统计学意义(P<0.05)。单因素Logistic回归分析提示,GLS、左室基底段收缩期纵向峰值应变(BLS)及左室下壁收缩期纵向峰值应变(I-LS)为术后Heart Model EF降低的影响因素(P<0.05),GLS、BLS及I-LS曲线下面积分别为0.693、0.817及0.702,临界值分别为-18.26%、-18.93%、-18.37%,敏感度分别为68%、79%及66%,特异性分别为93%、78%及91%。进一步多因素Logistic回归分析,提示仅有BLS用于预测中重度MR术后三维射血分数降低有统计学意义(P<0.05)。结论STI可为中重度MR病人在选择手术时机时提供可靠参考依据,左室GLS、BLS及I-LS均可用作中重度MR术后三维射血分数降低的预测因子,其中BLS临床价值更大。
基金supported by National Natural Science Foundation of China(Grant Nos.11271347 and 11171321)
文摘Modeling the mean and covariance simultaneously is a common strategy to efficiently estimate the mean parameters when applying generalized estimating equation techniques to longitudinal data. In this article, using generalized estimation equation techniques, we propose a new kind of regression models for parameterizing covariance structures. Using a novel Cholesky factor, the entries in this decomposition have moving average and log innovation interpretation and are modeled as the regression coefficients in both the mean and the linear functions of covariates. The resulting estimators for eovarianee are shown to be consistent and asymptotically normally distributed. Simulation studies and a real data analysis show that the proposed approach yields highly efficient estimators for the parameters in the mean, and provides parsimonious estimation for the covariance structure.
基金supported by the National Natural Science Foundation of China under Grant Nos.11271286,11271286,71171003,and 11226218Provincial Natural Science Research Project of Anhui Colleges under Grant No.KJ2011A032Anhui Provincial Natural Science Foundation under Grant Nos.1208085QA04 and 10040606Q03
文摘This paper considers large sample inference for the regression parameter in a partially linear regression model with longitudinal data and a-mixing errors. The authors introduce an estimated empirical likelihood for the regression parameter and show that its limiting distribution is a mixture of central chi-squared distributions. Also, the authors derive an adjusted empirical likelihood method which is shown to have a central chi-square limiting distribution. A simulation study is carried out to assess the performance of the empirical likelihood method.
