ABSTRACT The Emergency Department (ED) is an essential care setting for Veteran persons living with dementia (PLWDs), with 40% of community-dwelling PLWDs making at least one ED visit per year. One of the most impactful and costly elements of ED care is the decision to admit a patient to the hospital or discharge them home- the “dispo- sition” decision. ED providers must balance the risks of unnecessary admissions, such as delirium and functional decline, against the risks of discharge, which may result in return ED visits and hospitalizations. ED providers lack best practices to incorporate PLWD and caregiver values and preferences in the disposition decision when there is no serious illness that clearly requires admission. Shared decision making (SDM) tools can facilitate complex conversations between patients, caregivers, and ED providers, to ensure that patients and caregivers are involved in decisions about their care. The research proposed in this application is designed to develop a shared decision making tool to support ED dispositions that are aligned with PLWD and caregiver goals. With the support of her mentorship team, this proposal is also intended to support the continued career devel- opment of Dr. Justine Seidenfeld, an extremely promising emergency medicine physician-scientist, within the field of emergency care health services research. During this period of support, she will pursue didactic instruc- tion and further training to 1) advance her skills in methods for conducting research with PLWDs and their caregivers, 2) learn best practices to design and implement interventions aligned with end-user needs, and 3) develop skills for development and testing of SDM tools. The expected outcome of this proposal is to construct and pilot test a SDM tool to support high-quality ED dispositions for PLWDs. This study employs a sequential design based on the 3-step decision aid development process created by the International Patient Decision Aid Standards (IPDAS) collaboration. Aims 1 and 2 will address the first “under- stand user” step through quantitative and qualitative methods. Aim 1 will calculate home time (i.e., days alive and out of acute and post-acute settings) after an ED visit for a cohort of Veterans with dementia, and identify Veteran, ED facility, and visit type characteristics that are associated with variation in home time to suggest groups that may benefit from a customized SDM tool. Aim 2 will use qualitative interviews with Veteran PLWDs, their caregivers, and ED providers after an ED visit to assess their unmet needs, values, and preferences when making a disposition decision. To fulfill the “development/refinement” and “assessment” steps of the IPDAS de- velopment process, Aim 3a will create and iteratively refine a prototype SDM tool with feedback from a multidis- ciplinary collaborator panel, and Aim 3b will then use a iterative cohort pilot study design to assess the feasibility and acceptability among PLWDs, ca...