Vertical integration between insurers and providers is rapidly reshaping US health care, with acquisitions by UnitedHealth Group's Optum division playing a significant role. This study examined two dimensions of Optum's strategy: whether the physician practices it acquired shifted patients from hospital outpatient departments to less expensive ambulatory surgery centers (ASCs), and whether its ASC acquisitions affected prices charged to competing insurers. Analyzing 2013-21 Medicare claims, we found that acquisitions were not followed by a significant shift in ASC referral share. Our analysis of twenty-one acquired physician practices instead revealed a pattern consistent with strategic selection: Optum preferentially acquired practices that already had high rates of ASC use, a finding that held after we accounted for patient characteristics. Separately, using 2015-18 commercial claims, we found that Optum's acquisition of twenty-four ASCs was associated with an 11.0percent price increase, an effect that comprised both a broad increase in facility fees and a rise in professional fees that occurred only among Optum-employed physicians. These findings highlight important issues for market competition and costs.

Despite expanded insurance coverage after the Affordable Care Act, medical debt remains a significant burden for millions of Americans, particularly after acute medical events such as traumatic injuries. We evaluated the financial impact of hospitalization for acute traumatic injury, using data from a statewide trauma registry linked to consumer credit reports from the period 2019-21. Using a stacked difference-in-differences event study design, we compared financial outcomes for 12,823 injured patients versus 25,195 not-yet-injured matched controls. At eighteen months post-injury, the proportion of patients with medical debt in collections increased by 5.2percentage points (a 24percent relative increase compared with the pre-injury baseline), and the mean medical debt in collections (including patients with no debt) rose by $290 (a 76percent relative increase). Post-injury changes in bankruptcy filings peaked at 3.2 per 1,000 patients (a 6percent relative increase) at fifteen months post-injury. Financial hardship disproportionately affected uninsured, younger, lower-income, and privately insured patients, whereas those with Medicare and Medicaid experienced minimal change. These findings highlight persistent financial vulnerabilities, even among privately insured patients, and they underscore the need for policy enhancements that strengthen protections against the financial consequences of unanticipated acute medical events.

Medicaid adult dental coverage is an optional benefit that states often add or remove in response to budgetary pressures. The effect of these fluctuations on access to dental services is unclear. Using 2010-21 Health and Retirement Study data and a dynamic difference-in-differences event study, we examined the effects of removing versus adding Medicaid adult dental benefits among adults ages 50-64 with income up to 100percent of the federal poverty level. Eliminating benefits was associated with increased dental uninsurance (60.1percentage points) and any out-of-pocket spending in the past two years (20.2percentage points), as well as decreased dental visits in the past two years (-37.4percentage points) and edentulism (complete loss of all natural teeth; -13.4percentage points). Expanding benefits was associated with decreased dental uninsurance (-40.7percentage points) and any out-of-pocket spending (-36.5percentage points), as well as increased dental visits (22.1percentage points) and edentulism (16.9percentage points). Both changes were associated with increased unawareness of dental coverage (11.7 and 33.0percentage points, respectively). Several effects persisted up to eight years, indicating that Medicaid dental policy shifts have lasting implications. These findings underscore the importance of stable Medicaid dental coverage, particularly as Congress and states weigh large-scale Medicaid cuts.

Health care spending in the US reached $5.3trillion and increased 7.2percent in 2024, similar to growth of 7.4percent in 2023, as increased demand for health care influenced this two-year trend. As in 2023, the use and intensity of health care goods and services continued to grow rapidly in 2024, particularly for hospital care, physician and clinical services, and retail prescription drugs. The insured share of the population remained relatively high in 2024, at 91.8percent, after its peak in 2023 of 92.5percent. Health care spending growth continued to outpace overall economic growth in 2024, and as a result, the health care share of the economy increased from 17.7percent in 2023 to 18.0percent in 2024.

Housing insecurity, an important determinant of mental health, worsened during the COVID-19 pandemic in the US. The federal Emergency Rental Assistance (ERA) program sought to reduce housing insecurity among low-income renters. Using 2021-23 Household Pulse Survey data, we employed a quasi-experimental design to assess the effects of ERA on anxiety and depression symptoms and on mental health care use. We conducted causal mediation analyses to determine whether and how ERA affected these outcomes through indirect effects-by alleviating housing insecurity-or through direct effects, which freed up resources to seek care. ERA significantly reduced anxiety and depression symptoms through both indirect and direct effects. Among renters with anxiety or depression symptoms, it increased psychotherapy use through direct effects. Future rental assistance programs could strengthen these dual impacts by including features to improve both housing and health status-for example, by streamlining applications and expediting benefit delivery to provide resources that recipients can use to address urgent mental health needs even before full housing stability is achieved.

The rapid growth of clinical artificial intelligence (AI) applications poses a unique challenge to Medicare's prospective payment systems, with two issues at the forefront. First, the productivity gains from AI may dwarf those of previous non-AI innovations, but they are uncertain and will take time to realize. Second, AI forces the Centers for Medicare and Medicaid Services (CMS) to think very differently about software. For many clinical applications of AI, the software itself is the service. It does not make sense to treat this expense as overhead, but direct reimbursement will likely exceed the true cost of using AI. Finally, although CMS currently pays for only a small fraction of all AI-enabled medical devices approved by the Food and Drug Administration, Medicare may already be spending more on AI as a result of additional AI-generated findings and follow-up care.