Generalizing from clinical trial data: a case study. The risk of suicidality among pediatric antidepressant users.

For the results of randomized controlled clinical trials (RCTs) and related meta-analyses to be useful in practice, they must be relevant to a definable group of patients in a particular clinical setting. To the extent this is so, we say that the trial is generalizable or externally valid. Although concern about the generalizability of the results of RCTs is often discussed, there are few examples of methods for assessing the generalizability of clinical trial data. In this paper, we describe and illustrate an approach for making what we call generalizability judgments and illustrate the approach in the context of a case study of the risk of suicidality among pediatric antidepressant users. Copyright (c) 2008 John Wiley & Sons, Ltd.