Distinguishing between cost and value of psychological interventions: the case of long-versus short-term therapy

Background: Psychotherapy has been proven in numerous clinical studies to be an evidence-based intervention for many mental disorders. However, the question of the necessary “dose,” usually quantified as the number of therapy sessions, is a subject of ongoing debate. While proponents of long-term therapy emphasize significant but small additional effects, skeptics point to highly heterogeneous findings and escalating costs. Method: Using realistic assumptions about costs, benefits, and resource constraints of psychotherapy, we calculate the long-run public health impact of longer versus shorter therapies. Specifically, we incorporate training costs, limited availability of trained therapists, and short- versus long-term recovery trajectories. Results: Our simulation shows that, even under optimistic assumptions, short-term therapies lead to more patients in remission. A web application is provided to explore our calculations with customizable parameters and presets based on existing outcome studies. Conclusion: The discussion about the potential benefits of longer therapies should be expanded to not only include clinical outcomes and therapy dose, but also total treatment costs, including training requirements, and therapist availability in cost-effectiveness calculations.