Background: [The 2019 US Department of Health and Human Services Advancing American Kidney Health Initiative aims to “improve care coordination…for people living with kidney disease.” Accessing care from multiple systems and insurers can result in lapses in care coordination, and] patients with serious conditions, such as chronic kidney disease (CKD), are especially vulnerable to poorer outcomes from fragmented care. [While Medicaid expansion, as occurred with the Affordable Care Act (ACA),] is effective in improving access to health care and health outcomes for the uninsured, the significant number of Veterans enrolled in VA (who already have access to comprehensive care) who gained access to Medicaid with expansion face increased risk of care fragmentation. Increased use of non-VA care as a result of the MISSION Act poses similar risks.] Significance/Impact: As more Veterans access care from a mixture of VA and non-VA sources, VA needs to adopt strategies for cross-system care coordination to ensure effective and efficient care for Veterans. This requires understanding how Veterans utilize care when multiple options are available. Patients with advanced CKD have highly complex care needs. Lack of well-coordinated care may increase unnecessary care and worsen outcomes for such patients. Examining use and outcomes data will illustrate multiple aspects of access and care coordination for Veterans with chronic conditions and anticipates implementation of the MISSION Act. Innovation: [That some states opted out of ACA Medicaid expansion allows for a natural experiment where changes in quality of care and utilization over time can be compared between states that did and did not expand Medicaid. The team will use VA, Medicare, and recently-released post-expansion Medicaid claims data to evaluate how Medicaid expansion influences Veteran choices of health system use and CKD treatment.] Specific Aims: Aim 1: To determine the characteristics of Veterans and Veterans with CKD who are most likely to enroll in both Medicaid and VA. Aim 2: To determine the impact of dual enrollment on the utilization of health care services for Veterans with advanced CKD and to create a reference tool to enhance coordination for these patients. Aim 3: To evaluate differences in quality of health care and costs among Veterans with advanced CKD in states that have expanded Medicaid and those that have not. Methodology: Claims data [from 17 states (7 that expanded Medicaid in 2014 and 10 that did not) in the Medicaid Analytic eXtract (MAX) file for 2011-2014] are included. A difference-in-difference model will estimate the association of state Medicaid expansion with [changes in Veterans’ dual-enrollment status (VA and Medicaid) and in utilization and outcomes for Veterans with CKD. Utilization analyses will consider outpatient visits, emergency department visits and hospital admissions recorded in VA and Medicaid data. Outcomes to be considered are time-to-mortality, emergent ...