STUDYING INJURIES WITH CASE-CONTROL METHODS IN THE EMERGENCY DEPARTMENT

To study factors that cause or prevent injuries, it can be efficient t o use a case-control study design and select both cases and controls f rom patients seen in the ED. Bias in case ascertainment can be reduced by studying exposures that, aside from their influence On the risk of injury, are unrelated to the use of emergency care. The ideal control group often includes persons generally not seen in an ED: for example , those who experience the injury-producing event, such as a bicycle c rash, but who do not sustain serious injury. However, the exposure exp erience of the underlying population at risk sometimes can be closely approximated with information from selected persons seeking emergency care. With careful attention to the selection of study subjects, valid case-control studies of the causes of some injuries can be conducted in the ED.