Physician practice participation in accountable care organizations: the emergence of the unicorn.

Objective: To provide the first nationally based information on physician practice involvement in ACOs.

Data Sources/study Setting: Primary data from the third National Survey of Physician Organizations (January 2012-May 2013).

Study Design: We conducted a 40-minute phone survey in a sample of physician practices. A nationally representative sample of practices was surveyed in order to provide estimates of organizational characteristics, care management processes, ACO participation, and related variables for four major chronic illnesses.

Data Collection/extraction Methods: We evaluated the associations between ACO participation, organizational characteristics, and a 25-point index of patient-centered medical home processes.

Principal Findings: We found that 23.7 percent of physician practices (n = 280) reported joining an ACO; 15.7 percent (n = 186) were planning to become involved within the next 12 months and 60.6 percent (n = 717) reported no involvement and no plans to become involved. Larger practices, those receiving patients from an IPA and/or PHO, those that were physician-owned versus hospital/health system-owned, those located in New England, and those with greater patient-centered medical home (PCMH) care management processes were more likely to have joined an ACO.

Conclusions: Physician practices that are currently participating in ACOs appear to be relatively large, or to be members of an IPA or PHO, are less likely to be hospital-owned and are more likely to use more care management processes than nonparticipating practices.