Adapting dose-response methodology to improve clinical trial design for psychotherapies

Conventional randomized controlled trials (RCTs) have long served as the foundation of research in clinical psychology; however, most treatments for eating disorders show only modest effects on reduction of symptoms and maintenance of long-term remission. New options for psychotherapy treatment development research, beyond continuing to pursue additive or subpopulation approaches, are needed.

One option is to apply dose-response designs, which are commonplace in studies of pharmacology, toxicology, and medical research, and characterized by the evaluation of the amount of exposure (dose) to an intervention, and the resulting changes in body function or health (response).

Eating disorder interventions are particularly well-suited for dose-response treatment designs. The deadly nature of eating disorders makes it imperative that patients are not turned away for not being "ready" to engage with treatment. By identifying optimal doses, research will likely yield a more parsimonious course of treatment, which will lend itself to reduced costs, greater uptake, and reduced drop-out.

Limited use of within-subject designs in trials for patients with eating disorders has produced fast-track efficacy studies and omitted key elements in the treatment development pathway. To decrease reliance on RCT's, dose-response methods should be applied as an alternative study design.

Eating disorders are associated with medical and psychiatric comorbidities, poor quality of life, and high mortality. Access to evidence-based services for patients with eating disorders is limited, and identifying additional effective treatment options can be difficult because of challenges inherent to randomized-controlled trials. This manuscript describes an alternative trial methodology to maximize the information that can be gathered prior to utilizing a standard large-scale efficacy design.