Case-crossover design in air pollution epidemiology.
The case-crossover design was developed to study the effects of transient, short-term exposures on the risk of acute events, such as myocardial infarction, in the early 1990s. This paper illustrates how the principles of case-crossover design are related to the principles of crossover and case-control designs and stipulates the possibilities of case-crossover design in air pollution epidemiology. In the case-crossover design, the study population consists of subjects who have experienced an episode of the health outcome of interest. Similar to a crossover study, each subject serves as his or her own control. As in a matched case-control study, the inference is based on a comparison of exposure distribution rather than the risk of disease. The case-crossover study is most suitable for studying relations with the following characteristics: 1) the individual exposure varies within short time intervals; 2) the disease has abrupt onset and short latency for detection; and 3) the induction period is short. Case-crossover design allows use of routinely monitored air pollution information and at the same time makes it possible to study individuals rather than days as the unit of observation. Case-crossover design is amenable for studying the effects of varying short-term air pollution exposure on health outcomes with an abrupt onset, such as myocardial infarction or asthma attack.
Jaakkola
J J K
JJ
Institute of Occupational Health, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. j.jaakkola@bham.ac.uk
D000397:Air Pollution / Q000009:adverse effects*; D016022:Case-Control Studies; D018592:Cross-Over Studies; D015340:Epidemiologic Research Design; D005260:Female; D006801:Humans; D008297:Male; D012307:Risk Factors