PREDICTING THE OUTCOME OF TREATMENT

The clinical question-''Which treatment(s) for which patients with wha t set of subgrouping characteristics working by what mechanism(s)?''-r ests at the heart of differential therapeutics. Experimentally, this q uestion reduces to a test of how well we can predict the outcome of tr eatment using the treatment conditions plus other moderating and media ting variables. Reflecting the discussions held at a recent National I nstitute of Mental Health (NIMH) conference on psychosocial treatments , and using pediatric anxiety disorders as a case in point, we discuss the problem of prediction in treatment outcome studies from the stand point of definition of terms, using the general linear model of predic tion. We also outline types of studies that may be useful in testing p otential predictors, and put forward a possible matrix of predictor va riables as currently implemented in an NIMH-funded treatment outcome s tudy of pediatric obsessive-compulsive disorder (OCD). We conclude by making specific suggestions for implementing a broader approach to the study of predictors.