Accountable Care Organizations' Increase In Nonphysician Practitioners May Signal Shift For Health Care Workforce.

Both the number and the size of accountable care organizations (ACOs) in the Medicare Shared Savings Program have been increasing. The number of ACOs rose from 220 in 2013 to 548 in 2018, while the average number of participating clinicians in ACOs increased from 263 to 653. Although increases occurred for primary care physicians (from an average of 141 to 251) and medical specialists (from an average of 76 to 157), the increase for nonphysician practitioners (from an average of 47 to 245) was the largest. These differential increases changed the ACO workforce composition over time. The average proportion of nonphysician practitioners in ACOs grew from 18.1 percent to 38.7 percent, with a commensurate decline in the average share of primary care physicians from 60.0 percent to 42.2 percent. As value-based care models grow in prevalence, their evolving clinician composition may affect workforce patterns in the broader health care delivery system.