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Medicare ACO outcomes are indistinguishable from zero

August 14, 2019

Topics: Quote of the Day

By Mariétou H. Ouayogodé, PhD, Alexander J. Mainor, JD, MPH, Ellen Meara, PhD, Julie P. W. Bynum, MD, MPH, and Carrie H. Colla, PhD
JAMA Network Open, July 12, 2019



People with complex needs account for a disproportionate amount of Medicare spending, partially because of fragmented care delivered across multiple practitioners and settings. Accountable care organization (ACO) contracts give practitioners incentives to improve care coordination to the extent that coordination initiatives reduce total spending or improve quality.


To assess the association between ACO-reported care management and coordination activities and quality, utilization, spending, and health care system interactions in older adults with complex needs.

Design, Setting, and Participants

In this cross-sectional study, survey information on care management and coordination processes from 244 Medicare Shared Savings Program ACOs in the 2017-2018 National Survey of ACOs (of 351 Medicare ACO respondents; response rate, 69%) conducted from July 20, 2017, to February 15, 2018, was linked to 2016 Medicare administrative claims data. Medicare beneficiaries 66 years or older who were defined as having complex needs because of frailty or 2 or more chronic conditions associated with high costs and clinical need were included.


Beneficiary attribution to ACO reporting comprehensive (top tertile) care management and coordination activities.

Main Outcomes and Measures

All-cause prevention quality indicator admissions, 30-day all-cause readmissions, acute care and critical access hospital admissions, evaluation and management visits in ambulatory settings, inpatient days, emergency department visits, total spending, post–acute care spending, health care contact days, and continuity of care (from Medicare claims).


Among 1 402 582 Medicare beneficiaries with complex conditions, the mean (SD) age was 78 (8.0) years and 55.1% were female. Compared with beneficiaries assigned to ACOs in the bottom tertile of care management and coordination activities, those assigned to ACOs in the top tertile had identical median prevention quality indicator admissions and 30-day all-cause readmissions (0 per beneficiary across all tertiles), hospitalization and emergency department visits (1.0 per beneficiary in bottom and top tertiles), evaluation and management visits in ambulatory settings (14.0 per beneficiary [interquartile range (IQR), 8.0-21.0] in both tertiles), longer median inpatient days (11.0 [IQR, 4.0-33.0] vs 10.0 [IQR, 4.0-32.0]), higher median annual spending ($14 350 [IQR, $4876-$36 119] vs $14 229 [IQR, $4805-$36 268]), lower median health care contact days (28.0 [IQR, 17.0-44.0] vs 29.0 [IQR, 18.0-45.0]), and lower continuity-of-care index (0.12 [IQR, 0.08-0.20] vs 0.13 [IQR, 0.08-0.21]). Accounting for within-patient correlation, quality, utilization, and spending outcomes among patients with complex needs attributed to ACOs were not statistically different comparing the top vs bottom tertile of care management and coordination activities.

Conclusions and Relevance

The ACO self-reports of care management and coordination capacity were not associated with differences in spending or measured outcomes for patients with complex needs. Future efforts to care for patients with complex needs should assess whether strategies found to be effective in other settings are being used, and if so, why they fail to meet expectations.

From the Discussion

To measure whether ACO efforts to manage and coordinate care are associated with health care utilization and spending outcomes in groups likely to benefit from such services, we used data from the NSACO to form a care management and coordination index that plausibly targets older patients with complex health needs. We found wide variation in reported care management and coordination activities across MSSP participants. For example, when index scores were ranked by the level of care management activity reported, we observed large differences in the use of evidence-based approaches to care transitions for hospitalized patients. In multivariate analyses of patient-level measures for 244 ACO respondents, we found that high levels of care management and coordination intensity were not associated with significant differences in hospitalizations, inpatient days, E&M visits in ambulatory settings, spending, and health care system contact days despite large samples of beneficiaries in each group of ACOs.

Although our study is not definitive and includes several limitations, our estimates on various outcomes are indistinguishable from zero, indicating a call to invest in these areas with caution and to track local results in careful evaluations. Our results suggest that organizations should consider the effectiveness of investing heavily in care coordination activities that are difficult to implement.



By Don McCanne, M.D.

Regarding this study of outcomes among patients with complex needs in Medicare accountable care organizations, these authors report, “our estimates on various outcomes are indistinguishable from zero.” If there were any merit to ACOs, it should certainly show up in patients with complex needs.

As with many other studies that are reporting negligible results in their evaluations of accountable care organizations, these authors also recommend, “As ACOs focus on expanding care coordination and management efforts, it is important to continually evaluate the effectiveness of those programs for different patient populations.” More study of the same unsuccessful, mindless policy options?

There are endless conferences, seminars, and journal articles on accountable care organizations, all for naught. Yet where are the conferences on the single payer model of Medicare for All? These other conferences are a distraction from what we need to be doing – moving forward with enacting and implementing a model that would be truly effective, efficient, equitable, and affordable for all; Single Payer Medicare for All. Accountable care organizations are a dead end.

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About the Commentator, Don McCanne

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Don McCanne is a retired family practitioner who dedicated the 2nd phase of his career to speaking and writing extensively on single payer and related issues. He served as Physicians for a National Health Program president in 2002 and 2003, then as Senior Health Policy Fellow. For two decades, Don wrote "Quote of the Day", a daily health policy update which inspired HJM.

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