Volume 48 | Number 4 | August 2013

Abstract List

J. Michael McWilliams M.D., Ph.D., Michael E. Chernew Ph.D., Alan M. Zaslavsky Ph.D., Bruce E. Landon M.D., M.B.A., M.S.


To determine how the inclusion of post‐acute evaluation and management (E&M) services as primary care affects assignment of Medicare beneficiaries to accountable care organizations (s).

Data Sources

Medicare claims for a random 5 percent sample of 2009 edicare beneficiaries linked to merican edical ssociation roup ractice data identifying provider groups sufficiently large to be eligible for program participation.

Study Design

We calculated the fraction of community‐dwelling beneficiaries whose assignment shifted, as a consequence of including post‐acute E&M services, from the group providing their outpatient primary care to a different group providing their inpatient post‐acute care.

Principal Findings

Assignment shifts occurred for 27.6 percent of 25,992 community‐dwelling beneficiaries with at least one post‐acute skilled nursing facility stay, and they were more common for those incurring higher edicare spending. Those whose assignment shifted constituted only 1.3 percent of all community‐dwelling beneficiaries cared for by large ‐eligible organizations ( = 535,138), but they accounted for 8.4 percent of total edicare spending for this population.


Under current edicare assignment rules, s may not be accountable for an influential group of post‐acute patients, suggesting missed opportunities to improve care coordination and reduce inappropriate readmissions.