Assigning time-linked exposure status to controls in unmatched case-control studies: alcohol use and nearly lethal suicide attempts

In case-control studies, determination of alcohol consumption by cases imme diately prior to the injury event is often conceptually straightforward. Ho wever, determination of consumption status by controls is difficult because they lack a reference point, especially when cases and controls are not in dividually matched. We describe a method of assigning alcohol consumption s tatus to controls using a 24-hour drinking history, the distribution in tim e of case events, and the random assignment of a specific time period to ea ch control subject. This methodology offers a practical approach for determ ining alcohol consumption status among control subjects immediately prior t o a case event, when controls lack a reference point and have not been indi vidually matched to cases. Published in 2001 by John Wiley & Sons, Ltd.