Theory and practice of Case-Crossover Study Design

Ki, Moran

Abstract

A case-crossover study design is a method to assess the effect of transient exposures on the risk of onset of acute events. Which was introduced by Maclure in 1991 for Myocardial Infarction Onset Study. The design has been used to diverse fields of epidemiology such as injury, drug adverse events, air pollution and so on. The most valuable advantage of this design is unnecessary of control selection. To estimate relative risk, the exposure frequency during a window just before outcome onset is compared with exposure frequencies during control times rather than in control persons. One or more control times are supplied by each of the cases themselves. Self-matching of cases eliminates the threat of control-selection bias and increases efficiency. To application of the case-crossover design, we need to make sure several criteria and the possibility of specific bias. This review is designed to help the reader apply a case-crossover study design to their research fields by understanding general ideas, prior conditions and limitations of the design.