The case formulation approach to psychotherapy research revisited

Abstract

This article revisits the case formulation approach to psychotherapy outcome research, first proposed by Persons (1991). Persons asserted that randomized clinical trials (RCTs) of psychotherapy do not test the theoretical underpinnings of psychotherapy models since these trials standardize rather than individualize patient problems, ignore the link between individualized assessment and treatment as described in these models, and employ standardized rather than individualized treatment. This article assesses the current status of these claims, concluding that they remain valid today. A reformulated case formulation approach is described and research strategies proposed. Investigating the reformulated case formulation approach will require increased resources for case formulation training, the addition of treatment arms in effectiveness trials that include case-formulation-based interventions, and expanded RCTs that include systematic case studies. Key words: case formulation; randomized clinical trials (RCTs); psychotherapy research; treatment utility; clinical decision-making; case studies; clinical case studie