Project Summary/Abstract This study will evaluate the implementation of a population health approach to ensuring appropriate anticoagulant prescribing in a diverse collection of health systems. We will first evaluate the implementation and effectiveness of the direct oral anticoagulant (DOAC) dashboard that has been used in the Veterans Health Affairs (VHA) health system since 2016. This will be done by combining the VHA DOAC Dashboard database with the VHA Corporate Data Warehouse, national death index, and VHA fee-for-service datasets. The evaluation will follow the reach, effectiveness, adoption, implementation, maintenance (RE-AIM) evaluation model. Then, we will study the determinants of implementation success within the VHA, a fully integrated health system, as well as within a collection of non-VHA health systems participating in the Michigan Anticoagulation Quality Improvement Initiative (MAQI2) to identify differences in the barriers and facilitators of implementing this tool. To do this, we will conduct semi-structured interviews with key stakeholders at VHA sites with high, moderate, and low usage of the DOAC Dashboard as well as sites planning to implement the dashboard within MAQI2. These interviews will be evaluated using template analysis based on the Tailored Implementation in Chronic Disease (TICD) checklist and the Technology Acceptance Model. Finally, we will implement and evaluate the DOAC Dashboard within the MAQI2 consortium. We will again use the RE-AIM evaluation framework and leverage the existing MAQI2 database for analyses. Findings from this study will lead to improvements in safe management and a reduction in adverse drug events for patients prescribed oral anticoagulant medications. This study will also identify important differences in the implementation approach for population health tools between fully integrated and traditional health systems.