Medicare Shared Savings Program: Public Reporting and Shared Savings Distributions

Analysis of publicly reported organizational characteristics, shared savings distribution plans, and early financial success of accountable care organizations in the Medicare Shared Savings Program.
Published Online: August 18, 2015
John Schulz, BA; Matthew DeCamp, MD, PhD; and Scott A. Berkowitz, MD, MBA

Objectives: To determine if Medicare Shared Savings Program (MSSP) accountable care organizations (ACOs) are meeting public reporting requirements related to shared savings plans, to quantitate the composition of shared savings distribution plans, and to investigate whether early ACO success is associated with specific plan or ACO characteristics.

Study Design: Cross-sectional study.

Methods: ACO descriptive characteristics and distribution plan details were abstracted from official ACO websites for all 338 active MSSP ACOs launched through January 2014. Publicly available MSSP results from 2012 and 2013 start date ACOs were used to investigate associations with successful shared savings generation.

Results: Of current MSSP ACOs, 313 of 338 (93%) maintain a website, 284 of 338 (84%) provided at least a general statement about shared savings distributions, and 176 of 338 (52%) reported detailed allocation percentages to ACO participants. On average, ACOs reporting detailed allocations planned to give 63% (range = 0%-100%; SD = 26.3) to their primary care providers (PCPs), specialists, and/or hospitals, and 33% (range = 0%-100%; SD = 25.6) to infrastructure. ACOs including a hospital planned to give a larger average percentage to participating entities than those without (69% vs 58%; P = .01). ACOs planning to give >50% to their PCPs and specialists were more likely to have generated savings (P = .001), as were ACOs composed of >10 participating entities (P = .004).

Conclusions: Just over one-half of MSSP ACOs report detailed shared savings distribution plans online, and these plans vary widely. There appears to be no single shared savings distribution plan determinate of ACO success. Continued investigation of predictors for generating savings is needed to inform future shared savings models.

Am J Manag Care. 2015;21(8):546-553
Take-Away Points

Analysis of publicly reported organizational characteristics, shared savings distribution plans, and early financial success of accountable care organizations (ACOs) in the Medicare Shared Savings Program (MSSP) demonstrated that:
  • Most ACOs are meeting their public reporting requirements related to shared savings distribution plans.
  • ACOs vary widely in how they plan to distribute shared savings.
  • In a preliminary investigation using early MSSP ACO results, ACOs that planned to allocate the majority of shared savings to their primary care providers and specialists or were composed of more individual participating entities (ie, clinicians, clinician group practices, hospital, and/or other participating providers) were more likely to have generated savings.
More than 440 Medicare accountable care organizations (ACOs) have been established nationwide since the Affordable Care Act was passed in 2010.1,2 Medicare ACOs in the Medicare Shared Savings Program (MSSP) and Pioneer ACO programs voluntarily contract with Medicare to be responsible for the health outcomes and expenditures of a defined patient population. ACOs aim to promote higher-quality care and to reduce the growth of healthcare costs through improved care coordination, care management programs, information technology, and other interventions,3-5 and when ACOs succeed in these goals, they may share in the cost savings with Medicare. These potential “shared savings” are 1 important driver for ACO formation.6

Early results are modest.7 Of MSSP ACOs that initiated operations in 2012 or 2013, 118 (54%) lowered expenditures compared with benchmark projections. In total, these ACOs generated $383 million in net savings for Medicare during their first performance year, with 52 ACOs earning shared savings payments of more than $315 million.8 ACOs (and ACO-like models) continue to form, including in the commercial insurance sector and in state-based Medicaid programs.9-11 Nevertheless, significant questions remain about the financial viability of the ACO model.12,13

Specific regulatory requirements governing the MSSP provide an opportunity to examine important questions about what ACOs plan to do with their shared savings (ie, their “shared savings distribution plans”). The MSSP requires ACOs to initially submit their shared savings plan in their application to the MSSP program, and later to publicly report their distribution plans on required ACO websites.14 Guidance suggests that MSSP ACOs should also describe the percentage of total shared savings that will be allocated to infrastructure, primary care providers (PCPs), specialists, and hospitals in the ACO. Importantly, Medicare ACOs have flexibility in how they use shared savings, as long as use is consistent with the ACO program mission15; shared savings payments to beneficiaries, however, are not permitted.

Whether and how ACOs are meeting these policy requirements is unknown but of significant interest to all stakeholders,16,17 and patients may be interested in whether savings benefit them directly (eg, via new care programs and interventions) or indirectly (eg, via incentives to clinicians and hospitals to improve care quality).18 Although savings distribution to ACO PCPs and specialists is considered a key component of ACO success, how much and on what basis ACOs will do so is unspecified and unknown.19 Finally, ACO leaders and policy makers may be interested in what ACOs are doing regarding shared savings, because savings distribution plans likely reflect ACO strategic planning and what ACOs believe will help to incentivize desired care patterns.20

The objective of this study was to begin describing the landscape of how MSSP ACOs publicly report and plan to use their shared savings. We also conducted a preliminary investigation on whether certain ACO organizational characteristics appear to be associated with certain intended uses of shared savings. Finally, using early results from the MSSP, we examined whether certain organizational characteristics or shared savings distribution plan design elements are associated with ACO financial success.


Study Sample

We examined the official ACO websites for all 338 active MSSP ACOs initiated in April and July 2012, January 2013, and January 2014. At the time of our study, 5 ACOs had been approved to participate, but were not included in the CMS database of active ACOs (these were not included in this analysis).21 Website addresses were found using information available on the CMS website,21 but because the CMS website did not include website addresses for the January 2014 start date, we located these on the Internet. Among 338 ACOs, 322 had an available official website for review; all 16 ACOs without a website locatable by routine search methods were in the January 2014 group. Pioneer ACOs were excluded from analysis.

Data Abstraction Strategy

We designed a data abstraction strategy based upon information expected from MSSP public disclosure requirements14 and our study objectives, such as key ACO descriptive characteristics and composition, public reporting, and proposed shared savings distribution plan features (eg, percentage of distribution to infrastructure). A data abstraction form covering these domains is not publicly available to our knowledge; therefore, we developed one to capture desired data. We piloted a draft form on a subset (n = 30) of ACOs from the July 2012 group, then met and revised the form into a final version (eAppendix Table, available at This version was used to collect data on all MSSP ACOs from June 3 through July 23, 2014.

Some variables collected during data abstraction warrant explication. We hypothesized that organizational complexity might affect shared savings plan characteristics or ACO success, because larger, more complex organizations may complicate how an ACO forms and operates. As a proxy of complexity, we collected data on the number of individual entities (ie, clinicians, clinician group practices, hospital, and/or other participating providers) participating in each ACO. We refer to this as the number of “participating entities” in each ACO. To illustrate, by our definition, an integrated health system that forms an ACO within its existing organizational structure has 1 participating entity, whereas an ACO that forms from a private practitioner, a group practice, a multi-specialty group, and a hospital—all of whom were previously unaffiliated as de-fined by ACO rules—would have 4 participating entities. Our use of participating entity is generally consistent with the CMS regulatory definition of an ACO participant.15

We also hypothesized that ACO composition might affect shared savings plan characteristics or success. Although ACO regulations refer to ACO “providers,”15 we identified whether an ACO included hospitals, PCPs, and specialists from information provided on official ACO websites. Whether an individual or group practice in an ACO is primary care or specialty may not be evident by name alone; therefore, we independently confirmed these practices in all cases by reviewing their websites. Moreover, because an ACO composed of a single participating entity (such as an integrated health system) might include multiple clinician groups (such as PCPs, specialists, and hospitals) relevant for shared savings plan characteristics, we elucidated the composition of these ACOs in similar fashion.

We also believed it was important to assess whether involvement of an external stakeholder might affect shared savings distribution plans. We defined “external stakeholder involvement” as present when an external stakeholder investor or company representative (not apparently otherwise affiliated with an ACO participating entity) was present on the governing board, or when the distribution plan included distributions to investors/shareholders.


Shared savings distribution plans were analyzed to determine if the composition of ACOs or the presence of external stakeholders were associated with differences in distribution plans. Once early MSSP financial performance results became available, we examined the 58 ACOs that generated savings to determine whether certain ACO characteristics or shared savings distribution plans were associated with success in generating shared savings.22

Study data were collected and managed using REDCap version 5,23 and statistical analysis was conducted using STATA version 11 (StataCorp, College Station, Texas). For comparisons of categorical variables, a χ2 test was used, and for comparisons of means, an unpaired t test was utilized.


General ACO Characteristics

We found that 313 (93%) of the MSSP ACOs have information regarding their composition publicly available on their website. Of these ACOs, 131 (42%) have more than 20 participating entities, while 42 (13%) are composed of only 1 (Table). More specifically, 140 (45%) included PCPs, specialists, and hospitals, 124 (40%) had PCPs and specialists, while 49 (16%) were composed entirely of primary care physicians. Those meeting our definition of involving external stakeholders numbered 67 (21%).

In rare instances, other types of clinicians were noted as being in the ACO. These included chiropractors, podiatrists, hospice, clinical laboratories, home care, pharmacies, dentists, physical therapists, optometrists, senior living centers, social services, and others. Among all ACOs, 49 (14%) included an academic medical center (AMC).

Public Reporting of Shared Savings Distribution Plans

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