Flandre P
INSERM, Villejuif, France.
J Clin Epidemiol. 1996 Aug;49(8):899-905. doi: 10.1016/0895-4356(96)00044-3.
Prospective studies have as their goal the estimation of the survival function when the time to the specified event may be censored due to loss to follow-up or to the termination of the study before the event of interest occurs. In such a study, information about an auxiliary event, correlated to the event of interest, is often available. An example of such an auxiliary event in cancer studies is remission or relapse. A stochastic model was proposed by Lagakos, which utilizes this type of information in the analysis of survival studies [1]. The primary objective of using an auxiliary information is to improve the estimation of survival. This article proposes a method to estimate the variance of the estimator of the survival function S(t) for the model including such auxiliary information. Thus, we compute for different situations the relative efficiency of the estimator of S(t) using the stochastic model to the estimator of S(t) using only survival data. The method is applied to data from a prospective study of 379 HIV-seropositive homosexual men, of whom 31 developed AIDS. In our example, the auxiliary event is defined by the level of CD4 lymphocyte counts using distinct threshold values, for instance 200 cells/mm3, while the event of interest is the time to development of AIDS.
前瞻性研究的目标是估计生存函数，此时由于失访或在感兴趣的事件发生之前研究终止，到指定事件的时间可能被截尾。在这样的研究中，通常可以获得与感兴趣事件相关的辅助事件的信息。癌症研究中这种辅助事件的一个例子是缓解或复发。Lagakos提出了一个随机模型，该模型在生存研究分析中利用了这类信息[1]。使用辅助信息的主要目的是改善生存估计。本文提出了一种方法，用于估计包含此类辅助信息的模型中生存函数S(t)估计量的方差。因此，我们针对不同情况计算了使用随机模型的S(t)估计量相对于仅使用生存数据的S(t)估计量的相对效率。该方法应用于对379名HIV血清阳性同性恋男性的前瞻性研究数据，其中31人患了艾滋病。在我们的例子中，辅助事件由使用不同阈值（例如200个细胞/mm³）的CD4淋巴细胞计数水平定义，而感兴趣的事件是患艾滋病的时间。
