Miettinen O S
J Chronic Dis. 1985;38(7):543-48. doi: 10.1016/0021-9681(85)90039-6.
For valid selection of subjects in "case-control" (case-referent) studies it is critical to understand that these studies do not represent an alternative to cohort studies but, rather, to census-ascertainment of the facts about the study base. Specifically, in these studies, the fact-finding scheme is to obtain a census of the study base with respect to outcome, and then a census of the cases together with a sample of the base to gather information on the determinant(s) as well as modifiers and confounders. If the base is defined a priori (primary base), then the challenge is to devise a scheme to obtain a census of the cases in it and a sample of the base itself ("control" or reference series) that is representative of it, conditional on the covariates that will be controlled in the analysis of the data. On the other hand, if the definition of the base is secondary, a corollary of the way the cases are selected, then the case series is best viewed as the totality of the cases in the base as a matter of definition. The corresponding secondary base is the population experience in which each potential case, had it occurred, would have been included in the case series. Representative sampling of a secondary base tends to call for the use of subjects coming to the source of cases because of other conditions--conditions whose occurrence is known to be unrelated to the determinant under study and whose diagnosis and referral to the source are known to have the same relation to the determinant as those of the illness under study. With both types of base, primary and secondary, the accuracy of the information on the determinant should be comparable between the case and reference series, and this requirement of comparability, just as that of representativeness, can have important implications for the selection of the study subjects.
在“病例对照”（病例-对照）研究中，为了有效地选择研究对象，关键在于理解这些研究并非队列研究的替代方法，而是对研究基础事实进行普查确定的一种方式。具体而言，在这些研究中，事实调查方案是先对研究基础进行关于结局的普查，然后对病例进行普查，并从基础中抽取样本，以收集有关决定因素以及修饰因素和混杂因素的信息。如果基础是预先定义的（主要基础），那么挑战在于设计一种方案，以便在对数据进行分析时，基于将被控制的协变量，对其中的病例进行普查，并抽取能代表基础本身的样本（“对照”或参照系列）。另一方面，如果基础的定义是次要的，是病例选择方式的一个必然结果，那么从定义上讲，病例系列最好被视为基础中所有病例的总体。相应的次要基础是总体经验，即每个潜在病例如果发生，都会被纳入病例系列。对次要基础进行代表性抽样往往需要使用因其他情况而来到病例来源的研究对象，这些情况的发生已知与所研究的决定因素无关，而且其诊断和转诊到病例来源与所研究疾病的诊断和转诊与决定因素的关系相同。对于主要基础和次要基础这两种类型，病例组和参照组关于决定因素的信息准确性应该具有可比性，而这种可比性要求，就如同代表性要求一样，对研究对象的选择可能具有重要影响。
