COST-EFFECTIVENESS OF PSYCHOTHERAPY FOR CLUSTER C PERSONALITY DISORDERS

Purpose: To conduct a formal economic evaluation of psychotherapy for patients with avoidant, dependent, and obsessive-compulsive (i.e., cluster C) personality disorders (PD), leveraging primary clinical and economic data from the largest existing clinical trial of psychotherapy for PD.

Method: We developed a probabilistic decision-analytic model to assess the cost-effectiveness of five psychotherapy strategies for patients with cluster C PD:  long-term outpatient psychotherapy, short-term and long-term day hospital psychotherapy, and short-term and long-term inpatient psychotherapy. Model parameters were estimated using data from 466 patients with cluster C PD who were admitted to six specialist centers of psychotherapy in the Netherlands and assigned to one of the five treatment groups. The multiple propensity score method was used to control for initial differences between patient cohorts. Analyses were conducted from both societal and payer perspectives over a five year time horizon of the study. Outcomes were reported as cost per recovered patient-year and cost per quality-adjusted life year (QALY). Value of information analysis was used to estimate the expected net benefit of future research and to identify the parameters that were responsible for most of the decision uncertainty.

Results: From the societal perspective and below a threshold of €2,637 per recovered patient-year, short-term day hospital psychotherapy resulted in the highest expected net benefit; above the threshold, short-term inpatient psychotherapy was the most cost-effective choice. In terms of cost per QALY, the optimal strategy switched from short-term day hospital psychotherapy to short-term inpatient psychotherapy at a threshold value of €16,570 per QALY. From the payer perspective, the optimal strategy changed when the threshold was €9,874 per recovered patient-year and €66,302 per QALY. The categories of parameters that contributed to most of the decision uncertainty were treatment costs and the transition probabilities. The population expected value of perfect information (EVPI) was €445 million at a threshold value of €40,000 per QALY.

Conclusions: This study indicates that short-term day hospital psychotherapy and short-term inpatient psychotherapy are the optimal treatments for patients with cluster C PD in terms of cost per recovered patient-year and cost per QALY. The societal value of additional research is substantial, especially when prioritizing information on treatment costs and transition probabilities.