ERA-EDTA Registry, Department of Medical Informatics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
Nephron Clin Pract. 2010;116(2):c143-7. doi: 10.1159/000315883. Epub 2010 Jun 1.
In confounding, the effect of the exposure of interest is mixed with the effect of another variable. It is important to identify relevant confounders and remove the confounding effect as much as possible. There are three criteria that need to be fulfilled to determine whether a variable could be considered a potential confounder. The first criterion is that the variable needs to be associated with the exposure. The second criterion is that the variable needs to be associated with the outcome or disease. The third criterion is that the variable should not be an intermediate variable in the causal pathway between exposure and outcome. Only if all the criteria are fulfilled is the variable under question a confounder. If one incorrectly adjusts for a variable that is not a confounder, one risks overadjustment or adjustment for spurious associations. Confounders can be prevented from entering the study, during the design of a study, or if this is not possible, one can try to remove it during the analysis phase.
混杂是指感兴趣的暴露因素的效应与另一个变量的效应混杂在一起。确定相关的混杂因素并尽可能去除混杂效应非常重要。有三个标准需要满足才能确定一个变量是否可以被认为是潜在的混杂因素。第一个标准是该变量需要与暴露相关。第二个标准是该变量需要与结局或疾病相关。第三个标准是该变量不应是暴露和结局之间因果关系中的中间变量。只有满足所有标准，所讨论的变量才是混杂因素。如果一个人错误地调整了一个不是混杂因素的变量，就有可能过度调整或调整虚假关联。混杂因素可以在研究设计期间，在研究设计中预防进入研究，或者如果这不可能，则可以在分析阶段尝试去除它。
