Cost-Effectiveness of Collaborative Care for Depression and Comorbid Diabetes or CVD

This article, published in BMJ Open, presents an economic model that combines a decision tree and a Markov cohort model to investigate the long-term cost-effectiveness of collaborative care versus usual care for individuals with depression and comorbid diabetes and/or cardiovascular disease. Data from the COINCIDE trial informs the model input parameters. The COINCIDE trial is a randomized controlled trial of collaborative care versus usual care that enrolled 387 participants from 36 primary care general practices in North West England. Collaborative care consists of evidence-based low-intensity psychological treatments, delivered over 3 months and case management by a practice nurse and a Psychological Well Being Practitioner. The COINCIDE participants were only followed for 4 months, but the authors of this paper were also interested in long-term cost-effectiveness results. Therefore, a Markov cohort model is constructed for each study arm to extrapolate the findings from COINCIDE over a 24-months time horizon. The health states include: depressed, not depressed, dead. The perspective for the evaluation is that of the patient (health benefits) and health and social care services (costs) – an approximation of the societal perspective.

Results indicate that mean cost per participant of collaborative care is £317 (95% CI 284 to 350). Over 24 months, it was estimated that collaborative care is associated with greater healthcare usage costs (net cost £674 [95% CI -30 953 to 38 853]) and QALYs (net QALY gain 0.04 [95% CI -0.46 to 0.54]) compared with usual care, resulting in a cost per QALY gained of £16 123, and a likelihood of being cost-effective of 0.54 (assuming a willingness-to-pay threshold of £20 000/QALY).

Based on these findings the authors conclude that collaborative care is a potentially cost-effective long-term treatment for depression in patients with comorbid physical and mental illness.