Project Summary Life expectancy for people living with HIV (PWH) has increased substantially in the antiretroviral therapy (ART) era. Consequently, the Medicare program is anticipating a “silver tsunami” of PWH aging into program. There are substantial concerns about how HIV will affect treatment decisions, quality of care, and clinical outcomes of older PWH with age-associated multimorbidity, like Alzheimer’s disease and related dementias (ADRD), cardiovascular disease (CVD), and mental illness. Despite these concerns, we currently lack a national, comprehensive understanding of how quality and outcomes have changed for PWH over time, or the key patient, drug plan, market, community, and policy factors that influence care. Quality of care concerns are especially salient among historically marginalized populations that experience worse care quality at baseline, including racial and ethnic minorities, rural populations, and low-income adults dual-eligible for Medicaid and Medicare. A national strategy aimed at improving quality for older adults in the Medicare program is expansion of alternative payment models (APMs), including Accountable Care Organizations (ACOs), in which a group of healthcare providers take responsibility for assigned patients’ total costs and quality of care, and Bundled Payment Models (BPMs), which encourage cost reductions following admissions for specific clinical episodes. Although APMs have achieved modest savings and improvements in quality for Medicare beneficiaries generally, there is no empirical data evaluating whether APMs are effective for PWH. There are concerns that the quality and cost benchmarks in these models may lead clinicians in APMs to avoid high-risk patients like PWH, or when serving PWH, to limit necessary care due to aggressive cost-containment efforts. As the federal government expands APMs, it is critical that we understand the impact of APMs on the health of PWH. In this study, we will use national, longitudinal data (2005 to 2025) to pursue three aims. Aim 1 will evaluate changes in the quality of care and health outcomes among PWH compared to a matched population without HIV, and it will also identify the patient-, plan-, market-, clinician specialty-, and community-level factors associated with better quality, equity, and improved outcomes. Aim 2 will use a quasi-experimental study design to determine the impact of Medicare ACOs, the largest Medicare APM, on the quality of care and health outcomes of PWH. Finally, Aim 3 will determine whether Medicare BPMs, the second largest APM, improve or worsen quality and outcomes for PWH. Findings from this study will offer a national perspective on the key factors, including the Part D Drug Benefit design, on quality of care and health outcomes of PWH following age-eligibility for Medicare. We also propose the first national study to evaluate the impact of APMs on PWH. Our work will inform national clinical, public health and policy efforts aimed at impr...