Medicare Accountable Care Organizations and the Adoption of New Surgical Technology.

BACKGROUND: Dissemination of new surgical technology is a major contributor to healthcare spending growth. Accountable care organization (ACO) policy aims to control spending while maintaining quality. As a result, ACOs provide incentive for hospitals to selectively adopt newer procedures with high value. STUDY DESIGN: We conducted a retrospective cohort study using a 20% sample of national Medicare claims from 2010 to 2015. We identified hospitals that performed 1 of 6 sets of procedures: abdominal aortic aneurysm repair, aortic valve replacement, carotid endarterectomy or stent, lung lobectomy, colectomy, and prostatectomy. We identified hospitals participating in a Medicare Shared Savings Program ACO and a set of matched non-ACO control hospitals. We used a difference-in-differences approach to compare rate of surgical treatment and use of newer surgical technology for each set of procedures in ACO and non-ACO hospitals. RESULTS: We included 707 ACO-hospitals and 1,770 control hospitals. ACO hospitals performed surgery for carotid stenosis at a lower rate than non-ACO hospitals. There was no difference in the rate of surgical treatment for all other procedure sets. ACO hospitals were less likely to use an endovascular approach for abdominal aortic aneurysm repair (85.2% vs 88.2%, p < 0.001) and more likely to use a minimally invasive approach for lung lobectomy (42.2% vs 34.7%, p = 0.004) than non-ACO hospitals. In difference-in-differences analysis, ACO participation was not associated with any significant difference in use of surgical care for any of the 6 procedure sets, nor with any significant difference in use of newer surgical technology. CONCLUSIONS: Despite ACO policy incentives to selectively adopt newer surgical technology, ACO participation was not associated with differences in rate of surgery or use of newer surgical technology for 6 major surgical procedures.

Association Between Medicaid Expansion and Diagnosis and Management of Colon Cancer.

BACKGROUND: The Affordable Care Act facilitated improved insurance coverage for states that expanded Medicaid coverage, but the impact on cancer outcomes is unclear. This study compared changes in the diagnosis and management of colon cancer in states that did and did not participate in Medicaid expansion. STUDY DESIGN: Using a quasi-experimental difference-in-differences (DID) approach, we analyzed Medicaid and uninsured patients in the National Cancer Data Base during 2 time periods: pre (2011-2012) and post expansion (2015-2016). Patients in non-expansion states were compared with those in January 2014 expansion states with regard to changes in patient and facility characteristics, cancer staging, treatment decisions, and surgical outcomes. RESULTS: Along with increased Medicaid coverage (DID = 20.27; p < 0.001), patients in expansion states had an increase in stage I diagnoses (DID = 2.97; p = 0.035), distance traveled (miles, DID = 6.67; p = 0.005), and treatment at integrated network programs (DID = 2.67; p = 0.045). More early-stage patients were treated within 30 days (DID = 7.24; p = 0.035) and more stage IV patients received palliative care (DID = 5.01; p = 0.048). Among surgical patients, Medicaid expansion correlated with fewer urgent cases (< 7 days, DID = -5.88; p = 0.008) and more minimally invasive surgery (DID = 5.00; p = 0.022). There were no observed differences in postoperative outcomes or adjuvant chemotherapy. CONCLUSIONS: Medicaid expansion correlated with earlier diagnosis, enhanced access, and improved surgical care for colon cancer patients. These findings highlight the importance of improving health insurance coverage and can help guide future policy efforts.

Are ACOs Ready to be Accountable for Medication Use?

BACKGROUND: Accountable care organizations (ACOs) have the potential to lower costs and improve quality through incentives and coordinated care. However, the design brings with it many new challenges. One such challenge is the optimal use of pharmaceuticals. Most ACOs have not yet focused on this integral facet of care, even though medications are a critical component to achieving the lower costs and improved quality that are anticipated with this new model. OBJECTIVE: To evaluate whether ACOs are prepared to maximize the value of medications for achieving quality benchmarks and cost offsets. METHODS: During the fall of 2012, an electronic readiness self-assessment was developed using a portion of the questions and question methodology from the National Survey of Accountable Care Organizations, along with original questions developed by the authors. The assessment was tested and subsequently revised based on feedback from pilot testing with 5 ACO representatives. The revised assessment was distributed via e-mail to a convenience sample (n=175) of ACO members of the American Medical Group Association, Brookings-Dartmouth ACO Learning Network, and Premier Healthcare Alliance. RESULTS: The self-assessment was completed by 46 ACO representatives (26% response rate). ACOs reported high readiness to manage medications in a few areas, such as transmitting prescriptions electronically (70%), being able to integrate medical and pharmacy data into a single database (54%), and having a formulary in place that encourages generic use when appropriate (50%). However, many areas have substantial room for improvement with few ACOs reporting high readiness. Some notable areas include being able to quantify the cost offsets and hence demonstrate the value of appropriate medication use (7%), notifying a physician when a prescription has been filled (9%), having protocols in place to avoid medication duplication and polypharmacy (17%), and having quality metrics in place for a broad diversity of conditions (22%). CONCLUSIONS: Developing the capabilities to support, monitor, and ensure appropriate medication use will be critical to achieve optimal patient outcomes and ACO success. The ACOs surveyed have embarked upon an important journey towards this goal, but critical gaps remain before they can become fully accountable. While many of these organizations have begun adopting health information technologies that allow them to maximize the value of medications for achieving quality outcomes and cost offsets, a significant lag was identified in their inability to use these technologies to their full capacities. In order to provide further guidance, the authors have begun documenting case studies for public release that would provide ACOs with examples of how certain medication issues have been addressed by ACOs or relevant organizations. The authors hope that these case studies will help ACOs optimize the value of pharmaceuticals and achieve the "triple aim" of improving care, health, and cost. DISCLOSURES: There was no outside funding for this study, and the authors report no conflicts of interest related to the article. Concept and design were primarily from Dubois and Kotzbauer, with help from Feldman, Penso, and Westrich. Data collection was done by Feldman, Penso, Pope, and Westrich, and all authors participated in data interpretation. The manuscript was written primarily by Westrich, with help from all other authors, and revision was done primarily by Lustig and Westrich, with help from all other authors.

Using Nurse Care Managers Trained in the Serious Illness Conversation Guide to Increase Goals-of-Care Conversations in an Accountable Care Organization.

Background: Community-dwelling adults with serious illness benefit from conversations about their goals for care. Objective: We undertook a project to increase the number of serious illness conversations occurring in an accountable care organization (ACO) using a script delivered telephonically by nurse care managers. Design: Working with nurses previously trained in the basics of geriatric assessment and goals-of-care conversations, we used a quality improvement framework to modify the Ariadne Laboratories Serious Illness Conversation Guide to a six-question script. Subjects: Our target population was a subset of patients enrolled in a program within the ACO for patients who are high health care utilizers. Measures: After testing and modifying the script, we imbedded it into the initial nursing assessment in the electronic medical record. The electronic medical record prompts the nurses to ask the questions every three months to track changes in goals of care over time. Results: We have increased documentation of goals-of-care conversations from 33% of patients in the subpopulation during the first month of this project to 86% at the end of the first year. Nurse care managers' report that clinical outcomes are improved by these conversations. Conclusions: This project demonstrates a unique way to modify the Serious Illness Conversation Guide for use by nurses as part of a health care team. This project can be adapted by other health care organizations trying to increase goals-of-care conversations in their patient population.

The Power of Community: TMA Envisions Locally Focused ACO Model.

TMA is developing a promising, locally focused version of the accountable care organization (ACO) model that could help cover uninsured and underinsured Texans who fall in the gap or "hole" in the state's safety net: those who make too much money to qualify for Medicaid coverage as it's now administered in Texas, but also don't qualify for Medicare.

Prevalence of Screening for Food Insecurity, Housing Instability, Utility Needs, Transportation Needs, and Interpersonal Violence by US Physician Practices and Hospitals.

Importance: Social needs, including food, housing, utilities, transportation, and experience with interpersonal violence, are linked to health outcomes. Identifying patients with unmet social needs is a necessary first step to addressing these needs, yet little is known about the prevalence of screening. Objective: To characterize screening for social needs by physician practices and hospitals. Design, Setting, and Participants: Cross-sectional survey analyses of responses by physician practices and hospitals to the 2017-2018 National Survey of Healthcare Organizations and Systems. Responses were collected from survey participants from June 16, 2017, to August 17, 2018. Exposures: Organizational characteristics, including participation in delivery and payment reform. Main Outcomes and Measures: Self-report of screening patients for food insecurity, housing instability, utility needs, transportation needs, and experience with interpersonal violence. Results: Among 4976 physician practices, 2333 responded, a response rate of 46.9%. Among hospitals, 757 of 1628 (46.5%) responded. After eliminating responses because of ineligibility, 2190 physician practices and 739 hospitals remained. Screening for all 5 social needs was reported by 24.4% (95% CI, 20.0%-28.7%) of hospitals and 15.6% (95% CI, 13.4%-17.9%) of practices, whereas 33.3% (95% CI, 30.5%-36.2%) of practices and 8.0% (95% CI, 5.8%-11.0%) of hospitals reported no screening. Screening for interpersonal violence was most common (practices: 56.4%; 95% CI, 53.3%-2 59.4%; hospitals: 75.0%; 95% CI, 70.1%-79.3%), and screening for utility needs was least common (practices: 23.1%; 95% CI, 20.6%-26.0%; hospitals: 35.5%; 95% CI, 30.0%-41.0%) among both hospitals and practices. Among practices, federally qualified health centers (yes: 29.7%; 95% CI, 21.5%-37.8% vs no: 9.4%; 95% CI, 7.2%-11.6%; P < .001), bundled payment participants (yes: 21.4%; 95% CI, 17.1%-25.8% vs no: 10.7%; 95% CI, 7.9%-13.4%; P < .001), primary care improvement models (yes: 19.6%; 95% CI, 16.5%-22.6% vs no: 9.6%; 95% CI, 6.0%-13.1%; P < .001), and Medicaid accountable care organizations (yes: 21.8%; 95% CI, 17.4%-26.2% vs no: 11.2%; 95% CI, 8.6%-13.7%; P < .001) had higher rates of screening for all needs. Practices in Medicaid expansion states (yes: 17.7%; 95% CI, 14.8%-20.7% vs no: 11.4%; 95% CI, 8.1%-14.6%; P = .007) and those with more Medicaid revenue (highest tertile: 17.1%; 95% CI, 11.4%-22.7% vs lowest tertile: 9.0%; 95% CI, 6.1%-11.8%; P = .02) were more likely to screen. Academic medical centers were more likely than other hospitals to screen (49.5%; 95% CI, 34.6%-64.4% vs 23.0%; 95% CI, 18.5%-27.5%; P < .001). Conclusions and Relevance: This study's findings suggest that few US physician practices and hospitals screen patients for all 5 key social needs associated with health outcomes. Practices that serve disadvantaged patients report higher screening rates. The role of physicians and hospitals in meeting patients' social needs is likely to increase as more take on accountability for cost under payment reform. Physicians and hospitals may need additional resources to screen for or address patients' social needs.

Key Collaborative Factors When Medicaid Accountable Care Organizations Work With Primary Care Clinics to Improve Colorectal Cancer Screening: Relationships, Data, and Quality Improvement Infrastructure.

PURPOSE: Accountable Care Organizations (ACOs) are implementing interventions to achieve triple-aim objectives of improved quality and experience of care while maintaining costs. Partnering across organizational boundaries is perceived as critical to ACO success. METHODS: We conducted a comparative case study of 14 Medicaid ACOs in Oregon and their contracted primary care clinics using public performance data, key informant interviews, and consultation field notes. We focused on how ACOs work with clinics to improve colorectal cancer (CRC) screening - one incentivized performance metric. RESULTS: ACOs implemented a broad spectrum of multi-component interventions designed to increase CRC screening. The most common interventions focused on reducing structural barriers (n = 12 ACOs), delivering provider assessment and feedback (n = 11), and providing patient reminders (n = 7). ACOs developed their processes and infrastructure for working with clinics over time. Facilitators of successful collaboration included a history of and commitment to collaboration (partnership); the ability to provide accurate data to prioritize action and monitor improvement (performance data), and supporting clinics' reflective learning through facilitation, learning collaboratives; and support of ACO as well as clinic-based staffing (quality improvement infrastructure). Two unintended consequences of ACO-clinic partnership emerged: potential exclusion of smaller clinics and metric focus and fatigue. CONCLUSION: Our findings identified partnership, performance data, and quality improvement infrastructure as critical dimensions when Medicaid ACOs work with primary care to improve CRC screening. Findings may extend to other metric targets.

ACO Affiliated Hospitals Increase Implementation of Care Coordination Strategies.

BACKGROUND: Hospitals affiliated with Accountable Care Organizations (ACOs) may have a greater capacity to collaborate with providers across the care continuum to coordinate care, due to formal risk sharing and payment arrangements. However, little is known about the extent to which ACO affiliated hospitals implement care coordination strategies. OBJECTIVES: To compare the implementation of care coordination strategies between ACO affiliated hospitals (n=269) and unaffiliated hospitals (n=502) and examine whether the implementation of care coordination strategies varies by hospital payment model types. MEASURES: We constructed a care coordination index (CCI) comprised of 12 indicators that describe evidence-based care coordination strategies. Each indicator was scored on a 5-point Likert scale from 1="not used at all" to 5="used widely" by qualified representatives from each hospital. The CCI aggregates scores from each of the 12 individual indicators to a single summary score for each hospital, with a score of 12 corresponding to the lowest and 60 the highest use of care coordination strategies. RESEARCH DESIGN: We used state-fixed effects multivariable linear regression models to estimate the relationship between ACO affiliation, payment model type, and the use care coordination strategies. RESULTS: We found ACO affiliated hospitals reported greater use of care coordination strategies compared to unaffiliated hospitals. Fee-for-service shared savings and partial or global capitation payment models were associated with a greater use of care coordination strategies among ACO affiliated hospitals. CONCLUSION: Our findings suggest ACO affiliation and multiple payment model types are associated with the increased use of care coordination strategies.

Utilization of High-Cost Interventions for Targeted Clinical Conditions During the Early Stages of ACO Development in a Commercially Insured Population.

This study compared utilization patterns of high-cost services and medications for patients receiving care from Accountable Care Organization (ACO)-participating physicians and those receiving care from non-ACO physicians during the initial phases of ACO development in a commercially insured environment. Patients ≥18 years (≥40 years for chronic obstructive pulmonary disease [COPD]) with prevalent rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis, type 2 diabetes, COPD, or chronic low back pain between January 1, 2012, and August 31, 2014 were identified in the HealthCore Integrated Research DatabaseSM. Patients were assigned to the ACO cohort if their primary treating physician was contracted to the health plan through an ACO agreement. Each clinical condition was stratified for severity of illness. Cohort utilization patterns were compared for the 12-month period following the index encounter. The primary outcome measures show that there was no statistically significant utilization difference between the ACO and non-ACO cohorts for 90% of the 82 comparisons made. It is expected that some measures will achieve significant difference simply because of having this many comparisons, but no clear pattern was identified. This study did not observe statistically significant differences in utilization of high-cost services and medications between ACO and non-ACO cohorts with limited experience in the ACO model. Future analyses with longer study durations, at later stages of ACO development, tracking a more granular level of physician organizational structure, and with designs that integrate clinical and administrative data are essential to better understand the impact of payment innovation strategies using an ACO structure.

Interprofessional training: Geriatrics and palliative care principles for primary care teams in an ACO.

There is a well-described need to increase the competence of the primary care workforce in the principles of geriatrics and palliative care, and as value-based payment models proliferate, there is increased incentive for the acquisition of these skills. Through a Geriatric Workforce Enhancement Program grant, we developed an adaptable curriculum around commonly encountered topics in palliative care and geriatrics that can be delivered to multidisciplinary clinicians in primary care settings. All participants in this training were part of an Accountable Care Organization (ACO) and were motivated to improve to care for complex older adults. A needs assessment was performed on each practice or group of learners and the curriculum was adapted accordingly. With the use of patient education and screening tools with strong validity evidence, the participants were trained in the principals of geriatrics and palliative care with a focus on advance care planning and assessing for frailty and functional decline. Comparison of pre- and post-test scores demonstrated increased confidence and knowledge in goals of care and basic geriatric assessment. Participants described feeling more able to address needs, have conversations around goals of care, and more able to recognize patients who would benefit from collaboration with geriatrics and palliative care.

Organizational Attributes Associated With Medicare ACO Quality Performance.

PURPOSE: To evaluate associations between geographic, structural, and service-provision attributes of Accountable Care Organizations (ACOs) participating in the Medicare Shared Savings Program (MSSP) and the ACOs' quality performance. METHODOLOGY: We conducted cross-sectional and longitudinal analyses of ACO quality performance using data from the Centers for Medicare and Medicaid Services and additional sources. The sample included 322 and 385 MSSP ACOs that had successfully reported quality measures in 2014 and 2015, respectively. RESULTS: Results show that after adjusting for other organizational factors, rural ACOs' average quality score was comparable to that of ACOs serving other geographic categories. ACOs with hospital-system sponsorship, larger beneficiary panels, and higher posthospitalization follow-up rates achieved better quality performance. CONCLUSION: There is no significant difference in average quality performance between rural ACOs and other ACOs after adjusting for structural and service-provision factors. MSSP ACO quality performance is positively associated with hospital-system sponsorship, beneficiary panel size, and posthospitalization follow-up rate.

More Reform of the English National Health Service: From Competition Back to Planning?

The period of sustained financial austerity since 2009 has led to a shift in competition policy within the English National Health Service. Policymakers have directed their attention away from the preexisting priority to support quicker access to routine and planned hospital care and have focused instead on improving emergency, cancer, and general practitioner services. This has prompted the development of a new policy framework and, in particular, a desire to create collaborative health systems focused on specific populations. In addition, previous policy initiatives to engage the leadership of general practitioners in planning services have been revisited. The overall effect has been to shift emphasis away from competitive markets and back toward a planning approach.

Engaging Primary Care Providers to Reduce Unwanted Clinical Variation and Support ACO Cost and Quality Goals: A Unique Provider-Payer Collaboration.

This project was undertaken to reduce unneeded variation among practicing primary care clinicians participating in an accountable care organization (ACO) and to raise quality and reduce costs. This real-world, quasi-controlled experiment compared ACO target improvements between 3 participating geographic regions and members within the ProHealth ACO against nonparticipating regions and members. The authors used a novel care standardization initiative to engage participating providers. This was a 2-year longitudinal study with 6 rounds of serially measured provider care decisions and customized individual and group improvement feedback. Participating providers cared for online patient simulations as they would actual patients, and their care decisions were scored against evidence-based guidelines. This approach generated significant increases in evidence-based quality scores (+27%) and reductions in unneeded testing (-55%) in the patient simulations. Improvements in the online simulated patients correlated with improvements in patient-level ACO quality measures, which showed gains above and beyond the quasi-control group. Reductions calculated for spending on unneeded tests and specialist referrals exceeded $4.8 million. This study found that supporting practicing physicians in ACOs with evidence-based feedback significantly improved care and cost-efficiency.

The association between Medicare accountable care organization enrollment and breast, colorectal, and prostate cancer screening.

BACKGROUND: Despite the rapid diffusion of accountable care organizations (ACOs), the effect of ACO enrollment on cancer diagnosis, treatment, and survivorship remains unknown. The objective of this study was to determine whether Medicare Shared Savings Program (MSSP) ACO enrollment was associated with changes in screening for breast, colorectal, and prostate cancers. METHODS: The authors built a cohort of Medicare beneficiaries from 2006 through 2014 comprising 39,218,652 person-years of observation before and 17,252,345 person-years of observation after MSSP enrollment. The Centers for Medicare & Medicaid Services attribution methodology was recapitulated; and screening services were identified for breast, colorectal, and prostate cancer, implementing both sensitive and specific definitions of cancer screening. Adjusted difference-in-differences analyses were performed using linear regression to characterize changes in annual screening rates after ACO enrollment relative to contemporaneous changes in a non-ACO control group of Medicare beneficiaries. RESULTS: Medicare beneficiaries attributed to ACO-enrolled providers had higher rates of breast, colorectal, and prostate cancer screening before enrollment. A 1.8% relative reduction in breast cancer screening was observed among women attributed to ACO providers (P < .0001), a 2.4% relative increase was observed in colorectal cancer screening (P = .0259), and a 3.4% relative reduction was observed in prostate cancer screening among men attributed to ACO providers (P = .0025) compared with contemporaneous changes in non-ACO controls. CONCLUSIONS: Small-magnitude reductions were observed in breast and prostate cancer screening rates, and a small increase was observed in colorectal cancer screening associated with ACO enrollment. Although ACO enrollment does not appear to drive wholesale changes in cancer screening, small differences may map to meaningful changes in the epidemiology of screen-detected cancers among Medicare beneficiaries.

Hospitalist Value in an ACO World.

The accountable care organization (ACO) concept is advocated as a promising value-based payment model that could successfully realign the current payment system to financially reward improvements in quality and efficiency. Focusing on the care of hospitalized patients and controlling a substantive portion of variable hospital expenses, hospitalists are poised to play an essential role in system-level transformational change to achieve clinical integration. Especially through hospital and health system quality improvement (QI) initiatives, hospitalists can directly impact and share accountability for measures ranging from care coordination to implementation of evidence-based care and the patient and family caregiver experience. Regardless of political terrain, financial constraints in healthcare will foster continued efforts to promote formation of ACOs that aim to deliver coordinated, evidence-based, and patient-centered care. Hospitalists possess the clinical experience of caring for complex patients with multiple comorbidities and the QI skills needed to lead efforts in this new ACO era.

Advance Care Planning in an Accountable Care Organization Is Associated with Increased Advanced Directive Documentation and Decreased Costs.

BACKGROUND: Advance care planning (ACP) documents patient wishes and increases awareness of palliative care options. OBJECTIVE: To study the association of outpatient ACP with advanced directive documentation, utilization, and costs of care. DESIGN: This was a case-control study of cases with ACP who died matched 1:1 with controls. We used 12 months of data pre-ACP/prematch and predeath. We compared rates of documentation with logit model regression and conducted a difference-in-difference analysis using generalized linear models for utilization and costs. SETTING/SUBJECTS: Medicare beneficiaries attributed to a large rural-suburban-small metro multisite accountable care organization from January 2013 to April 2016, with cross reference to ACP facilitator logs to find cases. MEASUREMENTS: The presence of advance directive forms was verified by chart review. Cost analysis included all utilization and costs billed to Medicare. RESULTS: We matched 325 cases and 325 controls (51.1% female and 48.9% male, mean age 81). 320/325 (98.5%) ACP versus 243/325 (74.8%) of controls had a Healthcare Power of Attorney (odds ratio [OR] 21.6, 95% CI 8.6-54.1) and 172/325(52.9%) ACP versus 145/325 (44.6%) controls had Practitioner Orders for Life Sustaining Treatment (OR 1.40, 95% CI 1.02-1.90) post-ACP/postmatch. Adjusted results showed ACP cases had fewer inpatient admissions (-0.37 admissions, 95% CI -0.66 to -0.08), and inpatient days (-3.66 days, 95% CI -6.23 to -1.09), with no differences in hospice, hospice days, skilled nursing facility use, home health use, 30-day readmissions, or emergency department visits. Adjusted costs were $9,500 lower in the ACP group (95% CI -$16,207 to -$2,793). CONCLUSIONS: ACP increases documentation and was associated with a reduction in overall costs driven primarily by a reduction in inpatient utilization. Our data set was limited by small numbers of minorities and cancer patients.

Surgeon Participation in Early Accountable Care Organizations.

OBJECTIVE: We aimed to characterize the landscape of surgeon participation in early accountable care organizations (ACOs) and to identify specialty-, organization-, and market-specific factors associated with ACO participation. BACKGROUND: Despite rapid deployment of alternative payment models (APMs), little is known about the prevalence of surgeon participation, and key drivers behind surgeon participation in APMs. METHODS: Using data from SK&A, a research firm, we evaluated the near universe of US practices to characterize ACO participation among 125,425 US surgeons in 2015. We fit multivariable logistic regression models to characterize key drivers of ACO participation, and more specifically, the interaction between ACO affiliation and organizational structure. RESULTS: Of 125,425 US surgeons, 27,956 (22.3%) participated in at least 1 ACO program in 2015. We observed heterogeneity in participation by subspecialty, with trauma and transplant reporting the highest rate of ACO enrollment (36% for both) and plastic surgeons reporting the lowest (12.9%) followed by ophthalmology (16.0%) and hand (18.6%). Surgeons in group practices and integrated systems were more likely to participate relative to those practicing independently (aOR 1.57, 95% CI 1.50, 1.64; aOR 4.87, 95% CI 4.68, 5.07, respectively). We observed a statistically significant interaction (P <0.001) between surgical specialty and practice organization. Model-derived predicted probabilities revealed that, within each specialty, surgeons in integrated health systems had the highest predicted probabilities of ACO and those practicing independently generally had the lowest. CONCLUSIONS: We observed considerable variation in ACO enrollment among US surgeons, mediated at least in part by differences in practice organization. These data underscore the need for development of frameworks to characterize the strategic advantages and disadvantages associated with APM participation.