Robins J M, Gail M H, Lubin J H
Biometrics. 1986 Jun;42(2):293-9.
The authors consider several aspects of the design and analysis of synthetic case-control studies of cohort data under a proportional hazards model. First, in highly stratified data, consistent estimates of the relative risk are shown to result only if controls are sampled randomly with replacement from the entire risk set or without replacement from the noncases. Second, if previous controls are excluded from consideration as future controls but are included as cases if they fail, then inconsistent estimates of the relative risk can occur if "time" in the proportional hazards model represents an individual's chronological age and age at entry into follow-up is variable. On the other hand, if "time" represents time since the beginning of follow-up, estimates of the relative risk will be consistent, but the usual variance estimator will be inconsistent.
作者们考虑了比例风险模型下队列数据的合成病例对照研究的设计和分析的几个方面。首先，在高度分层的数据中，只有当对照从整个风险集合中进行有放回随机抽样或从非病例中进行无放回抽样时，相对风险的一致估计才会出现。其次，如果先前的对照被排除在未来对照的考虑范围之外，但如果它们发病则被纳入病例组，那么当比例风险模型中的“时间”代表个体的实际年龄且进入随访的年龄可变时，相对风险的估计可能会不一致。另一方面，如果“时间”代表随访开始后的时间，相对风险的估计将是一致的，但通常的方差估计量将是不一致的。
