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.

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.

Do Medicare Accountable Care Organizations Reduce Disparities After Spinal Fracture?

BACKGROUND: National changes in health care disparities within the setting of trauma care have not been examined within Accountable Care Organizations (ACOs) or non-ACOs. We sought to examine the impact of ACOs on post-treatment outcomes (in-hospital mortality, 90-day complications, and readmissions), as well as surgical intervention among whites and nonwhites treated for spinal fractures. MATERIALS AND METHODS: We identified all beneficiaries treated for spinal fractures between 2009 and 2014 using national Medicare fee for service claims data. Claims were used to identify sociodemographic and clinical criteria, receipt of surgery and in-hospital mortality, 90-day complications, and readmissions. Multivariable logistic regression analysis accounting for all confounders was used to determine the effect of race/ethnicity on outcomes. Nonwhites were compared with whites treated in non-ACOs between 2009 and 2011 as the referent. RESULTS: We identified 245,704 patients who were treated for spinal fractures. Two percent of the cohort received care in an ACO, whereas 7% were nonwhite. We found that disparities in the use of surgical fixation for spinal fractures were present in non-ACOs over the period 2009-2014 but did not exist in the context of care provided through ACOs (odds ratio [OR] 0.75; 95% confidence interval [CI] 0.44, 1.28). A disparity in the development of complications existed for nonwhites in non-ACOs (OR 1.09; 95% CI 1.01, 1.17) that was not encountered among nonwhites receiving care in ACOs (OR 1.32; 95% CI 0.90, 1.95). An existing disparity in readmission rates for nonwhites in ACOs over 2009-2011 (OR 1.34; 95% CI 1.01, 1.80) was eliminated in the period 2012-2014 (OR 0.85; 95% CI 0.65, 1.09). CONCLUSIONS: Our work reinforces the idea that ACOs could improve health care disparities among nonwhites. There is also the potential that as ACOs become more familiar with care integration and streamlined delivery of services, further improvements in disparities could be realized.

The Policy and Practice Legacy of the New Jersey Medicaid ACO Demonstration Project.

The New Jersey Medicaid Accountable Care Organization (ACO) Demonstration was created with a unique combination of features regarding ACO geography, involvement of managed care organizations (MCOs), and shared savings parameters. Ultimately, the Demonstration did not lead to a sustainable accountable care financing model and shared savings were deemphasized. Instead, the ACOs evolved into community health coalitions focused on coordinating and enhancing a wide range of activities in partnership with state government, private health systems, community leaders, and MCOs. Currently, the state is developing policy parameters to reposition the ACOs as regional partners to implement state-directed population health initiatives.

Association of Bundled Payments for Joint Replacement Surgery and Patient Outcomes With Simultaneous Hospital Participation in Accountable Care Organizations.

Importance: An increasing number of hospitals have participated in Medicare's bundled payment and accountable care organization (ACO) programs. Although participation in bundled payments has been associated with savings for lower-extremity joint replacement (LEJR) surgery, simultaneous participation in ACOs may be associated with different outcomes given the prevalence of LEJR among patients receiving care at ACO participant organizations and potential overlap in care redesign strategies adopted under the 2 payment models. Objective: To examine whether simultaneous participation in a Medicare Shared Savings Program (MSSP) ACO affects the association between hospitals' participation in LEJR episodes under the Bundled Payments for Care Improvement (BPCI) initiative and patient outcomes compared with participation in the BPCI initiative alone. Design, Setting, and Participants: This cohort study, conducted from January 1 to May 31, 2019, used 2011 to 2016 Medicare claims data and incorporated an instrumental variable with a difference-in-differences method among 483 008 fee-for-service Medicare beneficiaries undergoing LEJR surgery at 212 bundled payment participant hospitals, 105 coparticipant hospitals, and 1413 nonparticipant hospitals in the United States. Exposures: Hospital participation in both the BPCI initiative and the MSSP (coparticipants), BPCI only (bundled payment participants), or neither (nonparticipants). Main Outcomes and Measures: Changes in clinical outcomes and mean LEJR episode spending. Results: A total of 483 008 patients (mean [SD] age, 73.0 [8.4] years; 308 173 [63.8%] female) were included in the study. No differential changes were found in patient and hospital characteristics across participation groups. In adjusted analysis, coparticipants had 1.5% (95% CI, 0.7%-2.2%; P < .001) more unplanned readmissions than did bundled payment participants. Compared with bundled payment participants, coparticipants also had differentially greater decreases in hospital length of stay (adjusted difference-in-differences value, -5.3%; 95% CI, -7.1% to -3.5%; P < .001) and home health care use (adjusted difference-in-differences value, -3.4%; 95% CI, -4.5% to -2.3%; P < .001) and greater increases in postdischarge outpatient follow-up (adjusted difference-in-differences value, 2.1%; 95% CI, 0.9%-3.3%; P < .001). Coparticipants and bundled payment participants did not have differential changes in episode spending (adjusted difference-in-differences value, 0.4%; 95% CI, -0.7% to 1.6%; P = .46), although both groups had more decreased spending compared with nonparticipants. Conclusions and Relevance: Among bundled payment participants, coparticipation in ACOs was not associated with LEJR episode savings but was associated with differential changes in postacute care use patterns and unplanned readmissions. These findings support the longer-term benefits of LEJR bundles and suggest that coparticipants may adopt care redesign strategies that differ from hospitals with bundled payments only.

Medicare Shared Savings Program ACO network comprehensiveness and patient panel stability.

OBJECTIVES: The current Medicare Shared Savings Program (MSSP) accountable care organization (ACO) attribution methodology creates unpredictability for ACOs that are developing and deploying strategic initiatives aimed at improving value. The goal of this study is to determine if ACO network comprehensiveness is associated with the stability of assigned Medicare beneficiaries from 2013 to 2014. STUDY DESIGN: We utilized a beneficiary-level logistic regression model to determine association of network comprehensiveness with stable attribution to an MSSP ACO. METHODS: Using 2013 and 2014 Medicare fee-for-service beneficiary and provider files, we developed a measure of network comprehensiveness based on 2013 provider contracts, determined beneficiary attribution, and generated market-level measures. Additional population and quality measures were obtained from the US Census and the ACO Public Use File. RESULTS: Of the 1,317,858 observed beneficiaries, 84.38% were attributed to the same ACO in 2013 and 2014, and mean (SD) ACO network comprehensiveness was 0.30 (0.20). We found that a 0.10 increase in network comprehensiveness score significantly increased the odds of remaining attributed to the same ACO by 4.5% (P = .001). Patient panel stability was significantly associated with improved diabetes (P = .01) and hypertension (P = .02) control, timely access to care (P = .001), and delivery of health education (P = .03) over the 2-year period. CONCLUSIONS: The comprehensiveness of an MSSP ACO's contracted provider network is associated with stable patient assignment year to year. Patient panel stability may aid in the longitudinal management of some conditions.

ACO Contracts With Downside Financial Risk Growing, But Still In The Minority.

Success of the accountable care organization (ACO) model may require stronger financial incentives, such as including downside risk in contracts. Using the National Survey of ACOs, we explored ACO structure and contracts in 2012-18. Though the number of ACO contracts and the proportion of ACOs with multiple contracts have grown, the proportion bearing downside risk has increased only modestly.

A cluster-based approach for integrating clinical management of Medicare beneficiaries with multiple chronic conditions.

BACKGROUND: Approximately 28% of adults have ≥3 chronic conditions (CCs), accounting for two-thirds of U.S. healthcare costs, and often having suboptimal outcomes. Despite Institute of Medicine recommendations in 2001 to integrate guidelines for multiple CCs, progress is minimal. The vast number of unique combinations of CCs may limit progress. METHODS AND FINDINGS: To determine whether major CCs segregate differentially in limited groups, electronic health record and Medicare paid claims data were examined in one accountable care organization with 44,645 Medicare beneficiaries continuously enrolled throughout 2015. CCs predicting clinical outcomes were obtained from diagnostic codes. Agglomerative hierarchical clustering defined 13 groups having similar within group patterns of CCs and named for the most common CC. Two groups, congestive heart failure (CHF) and kidney disease (CKD), included 23% of beneficiaries with a very high CC burden (10.5 and 8.1 CCs/beneficiary, respectively). Five groups with 54% of beneficiaries had a high CC burden ranging from 7.1 to 5.9 (descending order: neurological, diabetes, cancer, cardiovascular, chronic pulmonary). Six groups with 23% of beneficiaries had an intermediate-low CC burden ranging from 4.7 to 0.4 (behavioral health, obesity, osteoarthritis, hypertension, hyperlipidemia, 'other'). Hypertension and hyperlipidemia were common across groups, whereas 80% of CHF segregated to the CHF group, 85% of CKD to CKD and CHF groups, 82% of cancer to Cancer, CHF, and CKD groups, and 85% of neurological disorders to Neuro, CHF, and CKD groups. Behavioral health diagnoses were common only in groups with a high CC burden. The number of CCs/beneficiary explained 36% of the variance (R2 = 0.36) in claims paid/beneficiary. CONCLUSIONS: Identifying a limited number of groups with high burdens of CCs that disproportionately drive costs may help inform a practical number of integrated guidelines and resources required for comprehensive management. Cluster informed guideline integration may improve care quality and outcomes, while reducing costs.

ACO Serious Illness Care: Survey And Case Studies Depict Current Challenges And Future Opportunities.

Care for people living with serious illness is suboptimal for many reasons, including underpayment for key services (such as care coordination and social supports) in fee-for-service reimbursement. Accountable care organizations (ACOs) have potential to improve serious illness care because of their widespread dissemination, strong financial incentives for care coordination in downside-risk models, and flexibility in shared savings spending. Through a national survey we found that 94 percent of ACOs at least partially identify their seriously ill beneficiaries, yet only 8-21 percent have widely implemented serious illness initiatives such as advance care planning or home-based palliative care. We selected six diverse ACOs with successful programs for case studies and interviewed fifty-three leaders and front-line personnel. Cross-cutting themes include the need for up-front investment beyond shared savings to build serious illness infrastructure and workforce; supporting the business case for organizational buy-in; how ACO contract specifications affect savings for serious illness populations; and using data and health information technology to manage populations. We discuss the implications of the recent Medicare ACO regulatory overhaul and other policies related to serious illness quality measures, risk adjustment, attribution methods, supporting rural ACOs, and enhancing timely data access.

Prostate cancer in the medicare shared savings program: are Accountable Care Organizations associated with reduced expenditures for men with prostate cancer?

OBJECTIVES: To assess whether Medicare expenditures for men with incident prostate cancer, treated in Accountable Care Organizations (ACOs) differ from those of men treated in non-ACOs. METHODS: Using the 20% Medicare sample, total charges for 1 year following an initial diagnosis of prostate cancer were abstracted from Medicare claims. Prostate cancer expenditures were calculated by subtracting total charges from the year prior to diagnosis. Propensity score weighting was used to balance baseline characteristics of men treated in ACOs and non-ACOs, and between treatment modalities (radiation, prostatectomy, and expectant management). A propensity score weighted regression model was then used to estimate mean expenditures for men with prostate cancer treated in ACOs and non ACOs and to test the association between ACO status and costs. RESULTS: We identified 3297 men treated in ACOs for localized prostate cancer versus 24,088 in the non-ACO cohort. The weighted total charges for each treatment modality were $32,358 (radiation), $27,662 (prostatectomy), and $11,134 (expectant management). In our propensity score weighted regression model, the association between charges and ACO status was not significant, nor was the interaction between treatment type and costs. This was true both overall, and in a stratified analysis by treatment type. CONCLUSIONS: There was no significant difference in Medicare spending on prostate cancer care based on provider ACO affiliation, regardless of treatment type. Although the effects of ACOs on clinical care are complex, this study adds to a growing body of evidence suggesting that ACOs fail to achieve significantly lower charges in certain clinical settings.

Recommended Cancer Screening in Accountable Care Organizations: Trends in Colonoscopy and Mammography in the Medicare Shared Savings Program.

PURPOSE: Accountable care organizations (ACOs) are a delivery and payment model designed to encourage integrated, high-value care. We designed a study to test the association between ACOs and two recommended cancer screening tests, colonoscopy for colorectal cancer and mammography for breast cancer. METHODS: Using the random 20% sample of Medicare claims, beneficiaries were attributed to ACO or non-ACO cohorts on the basis of providers' enrollment in the Medicare Shared Savings Program. An inverse probability of treatment weighting was used to balance patient characteristics between ACO and non-ACO cohorts. A propensity score-weighted, difference-in-differences analysis was then performed using the same provider groups in 2010-pre-ACO-as a baseline. A secondary analysis for older-nonrecommended-age ranges was performed. RESULTS: Prevalence of colonoscopy in recommended age ranges in ACOs from 2010 to 2014 increased from 15.3% (95% CI, 14.9% to 15.6%) to 17.9% (95% CI, 17.3% to 18.5%). This differed significantly from the change in non-ACOs (difference in differences, 1.2%; P < .001). Among women in ACOs, mammography prevalence rose from 53.7% (95% CI, 53.0% to 54.4%) to 54.9% (95% CI, 54.2% to 55.7%). In contrast to colonoscopy, the difference in mammography prevalence was not significantly different in ACO versus non-ACOs (difference in differences, 0.49%; P < .13). A similar pattern was also observed in older-nonrecommended-age ranges with significant difference in differences (ACO v non-ACO) in colonoscopy, but not mammography. CONCLUSION: The impact of ACOs on cancer screening varies between screening tests. Our results are consistent with a greater effect of ACOs on high-cost, high-complexity screening services, which may be more sensitive to integrated care delivery models.

Early Accountable Care Organization Results in End-of-Life Spending Among Cancer Patients.

BACKGROUND: Spending on cancer patients is substantial and has increased in recent years. Accountable care organizations (ACOs) are arguably the most important national experiment to control health-care spending. How ACOs are managing patients with cancer at the end of life (EOL) is largely unknown. We conducted this study with the objective of determining whether becoming an ACO is associated with subsequent changes in EOL spending or utilization among patients with cancer. METHODS: Using national Medicare claims from 2011 to 2015, we identified patients who died in 2012 (pre-ACO, n = 12 248) and 2015 (post-ACO, n = 12 248), assigning each decedent to a practice. ACOs were matched to non-ACOs within the same geographic region. We used a difference-in-difference model to examine changes in EOL spending and utilization associated with becoming an ACO in the Medicare Shared Savings Program for beneficiaries with cancer. RESULTS: We found that the introduction of ACOs had no meaningful impact on overall EOL spending in cancer patients (change in overall spending in ACOs = -$1687 vs -$1434 in non-ACOs, difference = $253, 95% confidence interval = -$1809 to $1304, P= .75). We found no changes in total patient spending by cancer type examined or by spending categories, including cancer-specific categories of radiation, therapy, and hospice services. Finally, emergency department visits, inpatient hospitalization, intensive care unit admissions, radiation therapy, chemotherapy, and hospice use did not meaningfully differ between ACO and non-ACO patients. CONCLUSIONS: The introduction of ACOs does not appear to have had any meaningful effect on EOL spending or utilization for patients with a cancer diagnosis.

Risk Adjustment In Medicare ACO Program Deters Coding Increases But May Lead ACOs To Drop High-Risk Beneficiaries.

The Medicare Shared Savings Program (MSSP) adjusts savings benchmarks by beneficiaries' baseline risk scores. To discourage increased coding intensity, the benchmark is not adjusted upward if beneficiaries' risk scores rise while in the MSSP. As a result, accountable care organizations (ACOs) have an incentive to avoid increasingly sick or expensive beneficiaries. We examined whether beneficiaries' exposure to the MSSP was associated with within-beneficiary changes in risk scores and whether risk scores were associated with entry to or exit from the MSSP. We found that the MSSP was not associated with consistent changes in within-beneficiary risk scores. Conversely, beneficiaries at the ninety-fifth percentile of risk score had a 21.6 percent chance of exiting the MSSP, compared to a 16.0 percent chance among beneficiaries at the fiftieth percentile. The decision not to upwardly adjust risk scores in the MSSP has successfully deterred coding increases but might discourage ACOs to care for high-risk beneficiaries in the MSSP .

Frailty Screening Using the Electronic Health Record Within a Medicare Accountable Care Organization.

BACKGROUND: The accumulation of deficits model for frailty has been used to develop an electronic health record (EHR) frailty index (eFI) that has been incorporated into British guidelines for frailty management. However, there have been limited applications of EHR-based approaches in the United States. METHODS: We constructed an adapted eFI for patients in our Medicare Accountable Care Organization (ACO, N = 12,798) using encounter, diagnosis code, laboratory, medication, and Medicare Annual Wellness Visit (AWV) data from the EHR. We examined the association of the eFI with mortality, health care utilization, and injurious falls. RESULTS: The overall cohort was 55.7% female, 85.7% white, with a mean age of 74.9 (SD = 7.3) years. In the prior 2 years, 32.1% had AWV data. The eFI could be calculated for 9,013 (70.4%) ACO patients. Of these, 46.5% were classified as prefrail (0.10 < eFI ≤ 0.21) and 40.1% frail (eFI > 0.21). Accounting for age, comorbidity, and prior health care utilization, the eFI independently predicted all-cause mortality, inpatient hospitalizations, emergency department visits, and injurious falls (all p < .001). Having at least one functional deficit captured from the AWV was independently associated with an increased risk of hospitalizations and injurious falls, controlling for other components of the eFI. CONCLUSIONS: Construction of an eFI from the EHR, within the context of a managed care population, is feasible and can help to identify vulnerable older adults. Future work is needed to integrate the eFI with claims-based approaches and test whether it can be used to effectively target interventions tailored to the health needs of frail patients.

Association Between Hospital Participation in Medicare Shared Savings Program Accountable Care Organizations and Readmission Following Major Surgery.

OBJECTIVE: To evaluate the effect of Medicare Shared Savings Program accountable care organizations (ACOs) on hospital readmission after common surgical procedures. SUMMARY BACKGROUND DATA: Hospital readmissions following surgery lead to worse patient outcomes and wasteful spending. ACOs, and their associated hospitals, have strong incentives to reduce readmissions from 2 distinct Centers for Medicare and Medicaid Services policies. METHODS: We performed a retrospective cohort study using a 20% national Medicare sample to identify beneficiaries undergoing 1 of 7 common surgical procedures-abdominal aortic aneurysm repair, colectomy, cystectomy, prostatectomy, lung resection, total knee arthroplasty, and total hip arthroplasty-between 2010 and 2014. The primary outcome was 30-day risk-adjusted readmission rate. We performed difference-in-differences analyses using multilevel logistic regression models to quantify the effect of hospital ACO affiliation on readmissions following these procedures. RESULTS: Patients underwent a procedure at one of 2974 hospitals, of which 389 were ACO affiliated. The 30-day risk-adjusted readmission rate decreased from 8.4% (95% CI, 8.1-8.7%) to 7.0% (95% CI, 6.7-7.3%) for ACO affiliated hospitals (P < 0.001) and from 7.9% (95% CI, 7.8-8.0%) to 7.1% (95% CI, 6.9-7.2%) for non-ACO hospitals (P < 0.001). The difference-in-differences of the 2 trends demonstrated an additional 0.52% (95% CI, 0.97-0.078%) absolute reduction in readmissions at ACO hospitals (P = 0.021), which would translate to 4410 hospitalizations avoided. CONCLUSION: Readmissions following common procedures decreased significantly from 2010 to 2014. Hospital affiliation with Shared Savings ACOs was associated with significant additional reductions in readmissions. This emphasis on readmission reduction is 1 mechanism through which ACOs improve value in a surgical population.

Early Impact of Medicare Accountable Care Organizations on Inpatient Surgical Spending.

OBJECTIVE: To evaluate whether hospital participation in accountable care organizations (ACOs) is associated with reduced Medicare spending for inpatient surgery. BACKGROUND: ACOs have proliferated rapidly and now cover more than 32 million Americans. Medicare Shared Savings Program (MSSP) ACOs have shown modest success in reducing medical spending. Whether they have reduced surgical spending remains unknown. METHODS: We used 100% Medicare claims from 2010 to 2014 for patients aged 65 to 99 years undergoing 6 common elective surgical procedures [abdominal aortic aneurysm (AAA) repair, colectomy, coronary artery bypass grafting (CABG), hip or knee replacement, or lung resection]. We compared total Medicare payments for 30-day surgical episodes, payments for individual components of care (index hospitalization, readmissions, physician services, and postacute care), and clinical outcomes for patients treated at MSSP ACO hospitals versus matched controls at non-ACO hospitals. We accounted for preexisting trends independent of ACO participation using a difference-in-differences approach. RESULTS: Among 341,675 patients at 427 ACO hospitals and 1,024,090 matched controls at 1531 non-ACO hospitals, patient and hospital characteristics were well-balanced. Average baseline payments were similar at ACO versus non-ACO hospitals. ACO participation was not associated with reductions in total Medicare payments [difference-in-differences estimate=-$72, confidence interval (CI95%): -$228 to +$84] or individual components of payments. ACO participation was also not associated with clinical outcomes. Duration of ACO participation did not affect our estimates. CONCLUSION: Although Medicare ACOs have had success reducing spending for medical care, they have not had similar success with surgical spending. Given that surgical care accounts for 30% of total health care costs, ACOs and policymakers must pay greater attention to reducing surgical expenditures.

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.