Health Care Utilization During the COVID-19 Pandemic - PROJECT SUMMARY/ABSTRACT The COVID-19 pandemic has created an unprecedented shock to the U.S. health care system and to care delivery for patients. As documented by the study team, the COVID-19 pandemic suddenly and dramatically changed health care utilization patterns, including a rapid escalation in use of telehealth services, an abrupt decline in in-person services, and a large volume of deferred services. It is unclear how these care patterns will evolve over the course of the pandemic (e.g., the degree to which deferred services will occur later, telehealth will substitute for in-person services, and new levels of telehealth services will be sustained), much less in the years following the COVID-19 pandemic, and how continuing care patterns will differ for socially and clinically vulnerable patient populations. Physician organizations (POs) face differing burdens in rapidly adopting telemedicine, and PO barriers to telemedicine adoption may be reflected in the outcomes of patients treated by these POs. The reduction in in-person care has placed financial stress on many POs, leading to concerns that many POs may go out of business or consolidate. The impacts of care reductions, the adoption of telemedicine as a new care delivery modality, and access to POs are likely to have larger effects among vulnerable patient populations, including lower-income, rural, and racial/ethnic minority populations, and patients with multiple chronic conditions. Understanding patient and provider responses to the COVID-19 public health crisis and the care patients receive, particularly those who are medically and socially vulnerable, is essential to inform immediate-term and longer-term policymaking intended to help the health delivery system respond to COVID- 19. We propose to conduct a set of analyses to 1) Estimate how health services have changed during the COVID-19 pandemic, the factors associated with changes in health service use, if health delayed care remains unmet once the COVID-19 pandemic subsides, how policy responses (social distancing policies and COVID- 19 vaccination) have impacted care delivery, and how these patterns differ for medically and socially vulnerable patient populations; 2) Asses PO barriers to adopting telemedicine and assess if PO adoption of telemedicine lessens adverse health outcomes, particularly among vulnerable patient populations; and 3) Examine if PO closure or consolidation due to COVID-19 leads to gaps in patient care continuity or access barriers among vulnerable patient populations. To do so, we will leverage the existing data assets and expertise of the RAND U19 Center of Excellence that the research team has built over the past 5 years. We will use 100% Medicare fee-for-service claims data. Findings from this study will help inform an array of immediate-term and longer-term policies and regulatory changes, including changes to payment policies, use of technology, financial assistance to providers to ensure their survival, and improving the ability of health systems to respond to how the COVID-19 pandemic has reshaped the US health care system.