Comparing the Clinical Work of Advanced Practice Professionals Working Within and Outside of Accountable Care Organizations

BACKGROUND: Health care delivery organizations increasingly employ advanced practice professionals (APPs) and participate in alternative payment models such as accountable care organizations (ACOs). Given the former's incentive to constrain spending, APPs' practice patterns may vary in ACO-participating versus non-ACO practices. OBJECTIVES: To compare outpatient care provided by APPs and physicians through ACO participation. RESEARCH DESIGN: We used multivariate linear regression to compare measures of workload allocation and billing across ACO-participating and non-ACO practices in 2022, controlling for practice size and market. SUBJECTS: A total of 91,149 practices, 12,072 in a Medicare Shared Savings Program ACO in 2022. MEASURES: We used 100% fee-for-service Medicare claims to identify ACO-participating and non-ACO practices. For every practice, we calculated the share of outpatient encounters provided by APPs rather than physicians and the share of APP-provided encounters billed indirectly to Medicare. We also calculated the share of annual wellness visits, chronic condition care management services, transitional care management services, and postoperative visits provided by APPs. RESULTS: APPs provided a smaller share of outpatient encounters at ACO-participating versus non-ACO practices, but were more likely to bill indirectly. Among most categories of routine services (eg, annual wellness visits and chronic condition management), APPs provided a smaller share of services at ACO-participating versus non-ACO practices. In the largest quartile of practices, APP practice patterns were more similar across ACO-participation status, and indirect billing was less likely within ACOs. CONCLUSIONS: Findings provide little evidence that ACOs deploy their APP workforce in a more cost-conscious manner than non-ACOs.