Resumen de Matched Cohort Methods for Injury Research
Peter Cummings, Barbara Mcknight, Sander Greenland
This article reviews the design and analysis of matched cohort studies of injuries where exposed study subjects are matched to others not exposed. We focus on the situation in which data are available for the matched groups with at least one member who had the study outcome, but data are absent or incomplete for matched groups that have no members with the outcome.
When matching is done in a case-control study, those with the outcome are matched to those without the outcome on certain confounder measures; this distorts the exposure status of the controls to be like that of the cases in regard to the matching variables (and perhaps other variables as well) (1). As a consequence, the selected controls may not represent the exposure experience of the entire population from which the cases were derived. Therefore, matching is a source of selection bias in a case-control study. The bias it produces can be removed in the analysis by accounting for the matching since, conditional on the values of the matching variables, controls will be representative of the source population.
