A new design for psychotherapy trials

In the current issue of Psychotherapy and Psychosomatics a new design for psychotherapy trials is presented. Mental disorders are highly prevalent and costly. Thus, their long-term outcome is of particular importance. Given this, it is surprising how little we know about both their naturalistic course and their long-term outcome after psychotherapy.

One of the main reasons for this gap may be that examining long-term effects in a controlled way is difficult, expensive and bears ethical and methodological risks. For example, treatment responders are often overrepresented in follow-ups while non-responders are lost to attrition or not followed up systematically. This may result in an overestimation of treatment effects. Related to this is the problem of differential retention, which occurs when high-risk patients are systematically excluded from one treatment condition, hereby subverting the effects of initial randomization of patients to treatment arms and again leading to distorted results. Adequate intent-to-treat analyses can partly solve these problems; however, non-responders are still lost.

future studies may consider an enhanced sequential approach, by (1) staging patients regarding relevant clinical characteristics; (2) informing them in detail on the nature of the trial, including potential problems; (3) focusing on non-responders; (4) randomizing these again to a psychotherapy specifically targeting non-response (augmentation) versus a control condition, and (5) including all patients in long-term follow-ups. Focusing on these issues is crucial for patients and clinicians to know whether treatments recommended by official guidelines can be expected to have long-lasting effects and what evidence-based options exist in case a treatment fails.