The VA Center for Medication Safety (VAMedSAFE) is charged with improving the safety of medication use for Veterans. VAMedSAFE’s interventions address the most serious, prevalent, and high-priority health conditions among Veterans, and yet they have a key limitation – they cannot account for medications received by Veterans outside VA. Over 80% of VA enrollees have access to medications through other forms of health insurance, including 50% with Medicare. There is strong evidence that receiving medications from multiple health systems poses serious health risks. The inability to integrate non-VA prescriptions into VA medication surveillance efforts has greatly diminished VA’s capacity to ensure safe prescribing to Veterans. Driven by this evidence, VA signed a groundbreaking agreement with the Centers for Medicare & Medicaid Services (CMS) to integrate CMS data on prescriptions filled by Veterans in Medicare into VAMedSAFE’s ongoing safety surveillance activities – something VA has never before been able to do. By the end of calendar year 2020, VAMedSAFE will have received and cleaned CMS data on dispensed Medicare prescriptions for all enrolled Veterans and will integrate these data into their ongoing medication surveillance activities. The objective of our proposed Dual Use of Medications (DUAL) Partnered Evaluation Initiative is to aid VAMedSAFE in developing and evaluating the roll-out of new quality enhancement tools using these combined CMS/VA data. Our evaluation has three aims, with the first aim split into two sub-aims. In Aim 1, we will work with VAMedSAFE to formatively evaluate the types of medications to prioritize when integrating CMS prescription data into their quality enhancement tools. Aim 1a will quantify how the integration of CMS prescription data could impact exposure measurement (e.g., number of patients identified as incident medication users) and outcomes (e.g., number of patients with a medication-related adverse event) for each ongoing VAMedSAFE surveillance program. Aim 1b will identify high-impact targets for new VA drug safety initiatives using CMS/VA data, using both quantitative and qualitative analyses. We will query the CMS/VA data to identify broad drug classes (e.g., hypoglycemics, opioids) that are frequently duplicated or overlapping between CMS and VA. Then, we will convene two interdisciplinary focus groups with key stakeholders to identify additional potential high-impact drug targets for future interventions using the CMS/VA data. In Aim 2, we will evaluate end users’ experiences with the first integration of CMS data into a VAMedSAFE drug safety dashboard focusing on direct-acting oral anticoagulant safety. Guided by the Practical, Robust Implementation and Sustainability Model (PRISM), we will conduct telephone interviews with end users of the dashboard (e.g., pharmacy directors, academic detailers, clinicians) to identify implementation barriers and facilitators and learn about their experiences receiv...