Project Summary/Abstract Direct oral anticoagulant medications are commonly used to treat or prevent thrombotic conditions, such as pulmonary embolism, deep vein thrombosis, and atrial fibrillation. However, up to 10-15% of patients receiving these medications get unsafe doses based on a patient's kidney or liver function, potential interactions with other medications, and indication for taking the medication. Alert systems may be beneficial for improving evidence-based prescribing, but can be burdensome. This study will improve upon existing alert systems by testing augmentations that encourage collaboration between prescribing health care providers (e.g., physicians, nurse practitioners) and expert pharmacists working in anticoagulation clinics and incorporating dynamic long-term monitoring of patient needs, as well as updates to evidence-based guidelines. Incorporating state-of-the-art and user-centered design principles, prescribing healthcare providers will be randomized to different types of electronic health record medication alerts when a patient has an unsafe anticoagulant prescription. We will identify which alerts are most effective at encouraging evidence-based prescribing, and will also test moderators to tailor alert delivery to when it most beneficial to ensure evidence-based anticoagulation prescribing. The specific aims of the project are to (1) implement and evaluate an EHR medication alert system to improve safe DOAC prescribing through prescriber-pharmacist collaboration; (2) tailor and refine medication alert delivery to minimize prescriber burden while maximizing effectiveness and actionability; and (3) assess patient acceptance of and barriers to anticoagulation pharmacist involvement in medication changes. Findings from this project will establish a framework for implementing prescriber- pharmacist collaboration for high risk medications, including anticoagulants. If effectively implemented at the more than 3000 anticoagulation clinics that exist nationally, hundreds of thousands of patients taking direct oral anticoagulants stand to benefit from safer, evidence-based healthcare.