Predicting response to cognitive therapy and interpersonal therapy, with or without antidepressant medication, for major depression: a pragmatic trial in routine practice

Background: Identifying patient characteristics that predict response within treatments (prognostic) or between treatments (prescriptive) can inform clinical decision-making. In this study, we sought to identify predictors of response to evidence-based treatments in a sample of depressed patients seeking help in routine practice.
Methods: Data come from a pragmatic trial of 174 patients with major depression who received an evidence-based treatment of their own choice: cognitive therapy (CT), interpersonal therapy (IPT), antidepressant medication (ADM) alone or in combination with either of the two psychotherapies. Patient characteristics measured at baseline were examined to see if they predicted subsequent response as measured with the Beck Depression Inventory (BDI) over the course of 26 weeks of treatment, using mixed regression modeling.
Results: Higher agoraphobia scores at baseline predicted more change in depression scores across treatments, irrespective of the treatment received. Physical functioning moderated the response to treatment: patients with high physical functioning fared better in combined treatment than patients with low physical functioning, whereas physical functioning did not predict a differential response in the psychotherapy group. Moreover, the lowest levels of physical functioning predicted an increase of depressive symptoms in combined treatment.
Limitations: A relatively small sample size, and selection of several predictors that were less theory-driven, which hampers the translation to clinical practice.
Conclusions: If replicated, the prognostic and prescriptive indices identified in this study could guide decision-making in routine practice. Development of more uniform requirements for the analysis and reporting of prediction studies is recommended.