Cost-effectiveness of guideline-based stepped and collaborative care versus treatment as usual for patients with depression – a cluster-randomized trial

BACKGROUND: Depression is associated with major patient burden. Its treatment requires complex and collaborative approaches. A stepped care model based on the German National Clinical Practice Guideline “Unipolar Depression” has been shown to be effective. In this study we assess the cost-effectiveness of this guideline based stepped care model versus treatment as usual in depression. METHODS: This prospective cluster-randomized controlled trial included 737 depressive adult patients. Primary care practices were randomized to an intervention (IG) or a control group (CG). The intervention consisted of a four-level stepped care model. The CG received treatment as usual. A cost-utility analysis from the societal perspective with a time horizon of 12 months was performed. We used quality-adjusted life years (QALY) based on the EQ-5D-3L as effect measure. Resource utilization was assessed by patient questionnaires. Missing values were imputed by ‘multiple imputation using chained equations’ based on predictive mean matching. We calculated adjusted group differences in costs and effects as well as incremental cost-effectiveness ratios. To describe the statistical and decision uncertainty cost-effectiveness acceptability curves were constructed based on net-benefit regressions with bootstrapped standard errors (1000 replications). The complete sample and subgroups based on depression severity were considered. RESULTS: We found no statically significant differences in costs and effects between IG and CG. The incremental total societal costs (+€5016; 95%-CI: [−€259;€10,290) and effects (+ 0.008 QALY; 95%-CI: [− 0.030; 0.046]) were higher in the IG in comparison to the CG. Significantly higher costs were found in the IG for outpatient physician services and psychiatrist services in comparison to the CG. Significantly higher total costs and productivity losses in the IG in comparison to the CG were found in the group with severe depression. Incremental cost-effectiveness ratios for the IG in comparison to the CG were unfavourable (complete sample: €627.000/QALY gained; mild depression: dominated; moderately severe depression: €645.154/QALY gained; severe depression: €2082,714/QALY gained) and the probability of cost-effectiveness of the intervention was low, except for the group with moderate depression (ICER: dominance; 70% for willingness-to-pay threshold of €50,000/QALY gained). CONCLUSIONS: We found no evidence for cost-effectiveness of the intervention in comparison to treatment as usual. TRIAL REGISTRATION: NCT, NCT01731717. Registered 22 November 2012 - Retrospectively registered.