ABSTRACT
The definition of and requirements for Medicare ACOs established in the ACA give organizations broad latitude in determining their organizational structure. Outside the Medicare context, there can be even greater flexibility: for example, Texas passed legislation in 2011 authorizing the creation of “health care collaborations” by physicians, hospitals, and other
health care providers; this legislation was intended to provide greater flexibility around the quality measures and payment methods used [60]. This intentional latitude enables providers to structure their ACOs according to what resources they already have, what local partners are interested in forming an ACO, and what is most needed in their local community. As a result, there is substantial variation both in how ACOs are organized and in how categories of ACOs are described or classified. These generally revolve around who the sponsoring entities [61], owners [62], and leaders [63] are, but no well-defined classification system has been agreed upon. The most comprehensive classification system takes into account the ACO’s number of full-time member physicians and the percentage of these who are PCPs, types of included provider organizations or services offered, ownership by an integrated delivery system, institutional leadership model, performance management system for accountability, and prior experience with non-fee-for-service payment mechanisms [64]. Based on these measures, three “clusters” of ACOs have been identified. These are outlined in Table 3.1.
