With their emphasis on coordinated care management and data collection, accountable care organizations (ACOs) are especially well positioned to improve the receipt and quality of preventive care services, from vaccines and cancer screenings to health risk assessments. To assess ACOs’ progress in promoting preventive care and identify the organizational characteristics that are associated with success in this area, Commonwealth Fund–supported researchers examined first-year results of ACOs participating in the Medicare Shared Savings Program (MSSP) and Pioneer program. The study focused on two domains of preventive care: disease prevention and wellness screening.

What the Study Found

  • ACOs in both the MSSP and Pioneer program lagged Medicare preferred provider organizations on the majority of measures related to disease prevention and wellness screening.
  • ACOs with relatively more specialists or fewer primary care physicians generally performed worse than their counterparts.
  • Having more Medicare ACO beneficiaries per primary care provider was associated with significantly better performance on composite scores related to disease prevention and wellness screening. The researchers posit that larger patient panels lead to more experience with, and greater focus on, quality measures.
  • Better performance on disease prevention also was associated with the inclusion of a hospital in the ACO network, greater electronic health record capabilities, a larger primary care workforce, and fewer minority enrollees.
  • Rural, physician-run ACOs that received start-up funding through the MSSP had significantly better performance, suggesting investments in labor and capital may help.


Two factors appear related to performance on preventive care quality: provider composition and upfront investment. Performance on disease prevention (e.g., vaccine and cancer screening) is more dependent on organizational structure and characteristics than performance on annual wellness screenings.