Carracedo-Martínez Eduardo, Tobías Aurelio, Saez Marc, Taracido Margarita, Figueiras Adolfo
Departamento de Medicina Preventiva y Salud Publica, Universidad de Santiago de Compostela, España.
Gac Sanit. 2009 Mar-Apr;23(2):161-5. doi: 10.1016/j.gaceta.2008.10.010. Epub 2009 Mar 20.
Case-crossover analysis is an observational epidemiological design that was proposed by Maclure in 1991 to assess whether a given intermittent or unusual exposure may have triggered an immediate short-term, acute event. The present article outlines the basics of case-crossover designs, as well as their applications and limitations. The case-crossover design is based on exclusively selecting case subjects. To calculate relative risk, exposure during the period of time prior to the event (case period) is compared against the same subject's exposure during one or more control periods. This method is only appropriate when the exposures are transient in time and have acute short-term effects. For exposures in which there is no trend, a unidirectional approach is the most frequent and consists of selecting one or more control periods prior to the case period. When the exposure displays a time trend (e.g., air pollution), a unidirectional approach will yield biased estimates, and therefore bidirectional case-crossover designs are used, which select control time intervals preceding and subsequent to that of the event. The case-crossover design is being increasingly used across a wide range of fields, including factors triggering traffic, occupational and domestic accidents and acute myocardial infarction, and those involved in air pollution and health and pharmacoepidemiology, among others. Insofar as data-analysis is concerned, case-crossover designs can generally be regarded as matched case-control studies and consequently conditional logistic regression can be applied. Lastly, this study analyzes practical examples of distinct applications of the case-crossover design.
病例交叉分析是一种观察性流行病学设计，由麦克卢尔于1991年提出，用于评估特定的间歇性或异常暴露是否可能引发即时的短期急性事件。本文概述了病例交叉设计的基本原理及其应用和局限性。病例交叉设计仅基于选择病例受试者。为了计算相对风险，将事件发生前一段时间（病例期）的暴露情况与同一受试者在一个或多个对照期的暴露情况进行比较。这种方法仅适用于暴露在时间上是短暂的且具有急性短期效应的情况。对于没有趋势的暴露，单向方法是最常用的，包括在病例期之前选择一个或多个对照期。当暴露呈现时间趋势（如空气污染）时，单向方法会产生有偏差的估计，因此使用双向病例交叉设计，即选择事件前后的对照时间间隔。病例交叉设计在广泛的领域中越来越多地被使用，包括引发交通、职业和家庭事故以及急性心肌梗死的因素，以及涉及空气污染与健康和药物流行病学等方面的因素。就数据分析而言，病例交叉设计通常可被视为匹配病例对照研究，因此可以应用条件逻辑回归。最后，本研究分析了病例交叉设计不同应用的实际例子。
