Dunlop D D, Tamhane A C, Chmiel J S, Phair J P
Center for Health Services and Policy Research, Northwestern University, Evanston, Illinois 60208.
J Biopharm Stat. 1994 Jul;4(2):129-46. doi: 10.1080/10543409408835078.
A model-based approach is developed to estimate the distribution of time from seroconversion to diagnosis with acquired immunodeficiency syndrome (AIDS) as a function of selected time-dependent covariates. The approach is applied to longitudinal data collected over 4 years of follow-up from 450 men seropositive for the human immunodeficiency virus (90 AIDS cases) and 62 seroconverters (nine AIDS cases) participating in the Chicago part of the Multicenter AIDS Cohort Study. Because of the periodic nature of monitoring, the seroconversion time is interval-censored for seroconverters and left-censored for seroprevalent cohort members; the end-point is right-censored for 413 individuals. Since serological monitoring is not continuous but only at regularly scheduled visit times, a model for the discrete hazard rate (DHR) is proposed that is a generalized linear model that relates the DHR to the covariate history through the complementary log-log link. Classification trees are used for preliminary screening of covariates to identify predictors of AIDS that should be incorporated into the DHR model. The missing seroconversion times for all men are imputed 100 times to obtain 100 completed datasets from which the parameters of the DHR are then estimated using the maximum-likelihood method. The final DHR model includes the following infection progression (marker) variables: CD4%, hemoglobin, p24 antigen, and CD4% x p24 antigen interaction. Using this DHR model, the discrete survival distribution of AIDS-free time is estimated for the given population. The jackknife procedure is used to assess the precision of the estimated survival distribution.
开发了一种基于模型的方法，以估计从血清转化到获得性免疫缺陷综合征（AIDS）诊断的时间分布，该分布是选定的时间依赖性协变量的函数。该方法应用于多中心艾滋病队列研究芝加哥部分中450名人类免疫缺陷病毒血清阳性男性（90例艾滋病病例）和62名血清转化者（9例艾滋病病例）在4年随访期间收集的纵向数据。由于监测具有周期性，血清转化时间对于血清转化者是区间删失的，对于血清阳性队列成员是左删失的；终点对于413名个体是右删失的。由于血清学监测不是连续的，而是仅在定期就诊时间进行，因此提出了一种离散风险率（DHR）模型，它是一种广义线性模型，通过互补对数-对数链接将DHR与协变量历史联系起来。分类树用于协变量的初步筛选，以识别应纳入DHR模型的艾滋病预测因子。对所有男性缺失的血清转化时间进行100次插补，以获得100个完整数据集，然后使用最大似然法估计DHR的参数。最终的DHR模型包括以下感染进展（标志物）变量：CD4%、血红蛋白、p24抗原以及CD4%×p24抗原相互作用。使用该DHR模型，估计给定人群无艾滋病时间的离散生存分布。采用刀切法评估估计生存分布的精度。
