This project will investigate trends in use of primary and specialty care among high-need, high-cost (HNHC) patients using the Medicare Current Beneficiary Survey (MCBS). Using MCBS, the project team will do a cross-sectional analysis to investigate the following: 1) utilization trends in use of primary and specialty care among HNHC patients enrolled in Medicare fee-for-service (FFS) and Medicare Advantage (MA); 2) utilization trends in areas with more or fewer primary care providers and specialists per capita; and 3) out-of-pocket costs for primary and specialty care visits per visit and per year. MCBS collects detailed, self-reported health care utilization and cost data. For FFS beneficiaries, survey responses are linked to claims and administrative data using a match algorithm. Visit-level cost data are also available for MA beneficiaries through survey-reported events. The team will link the Survey and Cost Supplement Files from 2010, 2013, and 2016 to perform a repeated cross-sectional analysis that captures population-level trends.