Wacholder S, Gail M, Pee D
National Cancer Institute, Biostatistics Branch, Rockville, Maryland 20892.
Biometrics. 1991 Mar;47(1):63-76.
We develop approximate methods to compare the efficiencies and to compute the power of alternative potential designs for sampling from a cohort before beginning to collect exposure data. Our methods require only that the cohort be assembled, meaning that the numbers of individuals Nkj at risk at pairs of event times tk and tj greater than or equal to tk are available. To compute Nkj, one needs to know the entry, follow-up, censoring, and event history, but not the exposure, for each individual. Our methods apply to any "unbiased control sampling design," in which cases are compared to a random sample of noncases at risk at the time of an event. We apply our methods to approximate the efficiencies of the nested case-control design, the case-cohort design, and an augmented case-cohort design, compared to the full cohort design, in an assembled cohort of 17,633 members of an insurance cooperative who were followed for mortality from prostatic cancer. The assumptions underlying the approximation are that exposure is unrelated both to the hazard of an event and to the hazard for censoring. The approximations performed well in simulations when both assumptions held and when the exposure was moderately related to censoring.
在开始收集暴露数据之前，我们开发了近似方法来比较从队列中抽样的替代潜在设计的效率并计算其功效。我们的方法仅要求队列已组建好，这意味着在事件时间(t_k)和大于或等于(t_k)的(t_j)这两个时间点处于风险中的个体数量(N_{kj})是已知的。为了计算(N_{kj})，需要知道每个个体的入组、随访、删失和事件发生历史，但不需要知道暴露情况。我们的方法适用于任何“无偏对照抽样设计”，在这种设计中，病例与事件发生时处于风险中的非病例随机样本进行比较。我们将我们的方法应用于一个由17633名保险合作社成员组成的已组建队列，该队列随访前列腺癌死亡率，以近似嵌套病例对照设计、病例队列设计和增强病例队列设计相对于全队列设计的效率。近似所基于的假设是暴露与事件风险以及删失风险均无关。当两个假设都成立且暴露与删失适度相关时，近似在模拟中表现良好。
