Background: Depression creates a substantial personal burden for affected individuals and their families, and produces significant economic and social hardships that affect society as a whole. In Belgium, depression is a leading cause of disability, measured as disability-adjusted life years. The COVID-19 pandemic has greatly exacerbated the already substantial health and socioeconomic consequences of depression and has led to major changes in the need for and delivery of mental health services. Integrating mental health services into primary care is the most viable way to closing existing treatment gaps. The majority of people with mental disorders treated in primary care have good outcomes, particularly when linked to a network of services at secondary level and in the community. A balanced model of depression care calls for a system with community-based mental health care, delivered by primary care physicians and supported by other professionals in an eco-system of care.
 Aim: Implementation of an integrated depression care (IDECA) intervention in two regions in Flanders, Belgium with evaluation of the intervention’s working components, its acceptance by patients and care providers, and the contextual conditions which needs to be fulfilled to safeguard success of the model of care.
 Methods: A scientific steering committee including multiple academic expertise areas and patient representatives guided the development of the intervention and its scientific evaluation. Moreover, feedback was obtained from the Flemish Institute for Primary Care (VIVEL), the Family Doctors Medical Association (Domus Medica), and a mental health interest group(Psyche VZW). This resulted in an implementation design without control group and a targeted heterogeneous patient population with depression to obtain real-world evidence. IDECA consists of three intervention pillars: (i) the integration of two reference persons mental health (case management function) into general medical practice and who provide diagnostic support, coordination, follow up care, and patient education; (ii) the implementation of a validated shared care treatment protocol; and (iii) professional training on depression screening and management. The three pillars will be further operationalized in co-creation with the selected regions. The intervention will run for 15 months.
 Data will be collected from both participating care providers and patients. Evaluation will take place using a Realist Evaluation approach in combination with the NoMad questionnaire for care providers which measures the four implementation metrics of the Normalization Process Theory: i. coherence, ii. cognitive participation, iii. collective action, and iv. reflexive monitoring. NoMad process data will serve as a basis for semi-structured qualitative research on Context-Mechanism-Outcome constellations. Questionnaires will be used to measure depression and anxiety levels, health literacy, quality of life, patient satisfaction, therapy adherence and self-efficacy, and healthcare resource utilization in patients.
 Results: Patient enrollment will start at the beginning of 2023. Preliminary data on patient characteristics and first data on care providers’ acceptance and engagement with the IDECA project will be presented, next to the co-creative development process of the intervention.
 Conclusion: The IDECA-study aims at the implementation of integrated depression care and evaluation of its feasibility in two different regions in Belgium.