Context The Centers for Medicare & Medicaid Services (CMS) recently launched
accountable care organization (ACO) programs designed to improve quality and slow cost
growth. The ACOs resemble an earlier pilot, the Medicare Physician Group Practice
Demonstration (PGPD), in which participating physician groups received bonus payments if
they achieved lower cost growth than local controls and met quality targets. Although
evidence indicates the PGPD improved quality, uncertainty remains about its effect on costs …