BackgroundDepression is a widespread and serious disease often accompanied by a high degree of suffering and burden of disease. The lack of integration between different care providers impedes guideline-based treatment. This constitutes substantial challenges for the health care system and also causes considerable direct and indirect costs. To face these challenges, the aim of this project is the implementation and evaluation of a guideline-based stepped care model for depressed patients with six treatment options of varying intensity and setting, including low-intensity treatments using innovative technologies.Methods/designThe study is a randomized controlled intervention trial of a consecutive sample of depressive patients from primary care assessed with a prospective survey at four time-standardized measurement points within one year. A cluster randomization at the level of participating primary care units divides the general practitioners into two groups. In the intervention group patients (n = 660) are treated within the stepped care approach in a multiprofessional network consisting of general practitioners, psychotherapists, psychiatrists and inpatient care facilities, whereas patients in the control condition (n = 200) receive routine care. The main research question concerns the effectiveness of the stepped-care model from baseline to t3 (12 months). Primary outcome is the change in depressive symptoms measured by the PHQ-9; secondary outcomes include response, remission and relapse, functional quality of life (SF-12 and EQ-5D-3 L), other clinical and psychosocial variables, direct and indirect costs, and the incremental cost-effectiveness ratio. Furthermore feasibility and acceptance of the overall model as well as of the separate treatment components are assessed.DiscussionThis stepped care model integrates all primary and secondary health care providers involved in the treatment of depression; it elaborates innovative and evidence-based treatment elements, follows a stratified approach and is implemented in routine care as opposed to standardized conditions. In case of positive results, its sustainable implementation as a collaborative care model may significantly improve the health care situation of depressive patients as well as the interaction and care delivery of different care providers on various levels.Trial registrationThis study is registered with ClinicalTrials.gov, number NCT01731717 (date of registration: 24 June 2013).

Guidelines recommend stepped and collaborative care models (SCM) for depression. We aimed to evaluate the effectiveness of a complex guideline-based SCM for depressed patients. German primary care units were cluster-randomised into intervention (IG) or control group (CG) (3:1 ratio). Adult routine care patients with PHQ-9 ≥ 5 points could participate and received SCM in IG and treatment as usual (TAU) in CG. Primary outcome was change in PHQ-9 from baseline to 12 months (hypothesis: greater reduction in IG). A linear mixed model was calculated with group as fixed effect and practice as random effect, controlling for baseline PHQ-9 (intention-to-treat). 36 primary care units were randomised to IG and 13 to CG. 36 psychotherapists, 6 psychiatrists and 7 clinics participated in SCM. 737 patients were included (IG: n = 569 vs. CG: n = 168); data were available for 60% (IG) and 64% (CG) after 12 months. IG showed 2.4 points greater reduction [95% confidence interval (CI): −3.4 to −1.5, p < 0.001; Cohen’s d = 0.45] (adjusted PHQ-9 mean change). Odds of response [odds ratio: 2.8; 95% CI: 1.6 to 4.7] and remission [odds ratio: 3.2; 95% CI: 1.58 to 6.26] were higher in IG. Guideline-based SCM can improve depression care.

In summary, using a hierarchical approach, it was possible to assign different levels of evidence to the various treatment options for depression.