# Cost-utility analysis of a collaborative and stepped care model in patients with mental disorders in German primary care (the COMET study)

## TL;DR

A study in Germany found that a new mental health care model was not more cost-effective than usual care for patients with common mental disorders over 12 months.

## Contribution

The study evaluates the cost-effectiveness of a collaborative and stepped care model for mental disorders in routine German primary care.

## Key findings

- The CSC model had similar quality-adjusted life years and total costs compared to treatment as usual.
- The CSC model had higher costs for outpatient mental health services, but was unlikely to be cost-effective.
- The probability of cost-effectiveness was 35% at a willingness-to-pay of 0€ and 34% at 50,000€ per QALY.

## Abstract

In order to reduce the health burden and the health care costs caused by the most common mental disorders, health care systems throughout Europe have tried to improve services and treatment choices. Recently, a collaborative and stepped care (CSC) model for patients with depressive, anxiety, somatoform or alcohol-related disorders and their comorbidities was developed and implemented under routine care conditions in Germany. The aim of this study was to determine the cost-effectiveness of this CSC model from a societal perspective with a 12-month follow-up.

This study was part of a cluster-randomized controlled trial to compare a CSC model with treatment as usual (TAU) in patients with depressive, anxiety, somatoform or alcohol-related disorders and their comorbidities in German routine care. The cost-effectiveness of the CSC model compared with TAU was analyzed based on the incremental cost-utility ratio (ICUR) with quality-adjusted life years (QALYs) based on the EQ-5D-5L index as measure of health effect. The uncertainty of the ICUR was assessed using cost-effectiveness acceptability curves based on net-benefit regressions.

In total, n = 307 patients in the CSC and n = 308 patients in the TAU group were included, with a mean age of 38 and 43 years, respectively. There were no differences in mean QALYs and total costs between the CSC (0.86 QALY, 27,174€) and the TAU group (0.86 QALY, 26,441€). Only the adjusted mean costs for outpatient mental health services were higher in the CSC group (+685€; 95% CI 398€ to 972€; p < 0.001). The probability of cost-effectiveness of the CSC model was 35% at a willingness-to-pay (WTP) of 0€ and 34% at a WTP of 50,000€ per additional QALY.

The evaluated CSC model was unlikely to be cost-effective compared with TAU from a societal perspective for patients with depressive, anxiety, somatoform or alcohol-related disorders and their comorbidities during the 12-month follow-up period. The higher mean costs for outpatient mental health services might indicate that general practitioners in the CSC group were able to refer patients to psychotherapists and psychiatrists more frequently through the network of health care providers.

ClinicalTrials.gov: NCT03226743. Registration date: 24/7/2017.

The online version contains supplementary material available at 10.1186/s12888-025-07428-5.