Analysis of the AHRQ Compendium of U.S. Health Systems Shows System Growth Continues but Benefits Remain Unclear

Analysis of the AHRQ Compendium of U.S. Health Systems Shows System Growth Continues but Benefits Remain Unclear

Medical professionals gather in hallway

Mathematica has a longstanding focus on describing the roles of clinicians, practice settings, and delivery organizations in caring for diverse populations and in assessing public and private policies intended to improve this care. These roles and policies have only increased in importance as communities experience the reorganization of local health care into complex integrated delivery systems—networks of hospitals and medical practices that provide comprehensive services. At the same time, many employers and families struggle with the growing costs of care. Some experts have posited that systems can improve the delivery of high-value care, but others have raised concerns about their growth. These concerns are supported by a review of past evidence conducted by Mathematica and the Agency for Healthcare Research and Quality (AHRQ) that suggests consolidation into health systems often results in higher costs and prices with few, if any, gains in quality.

To help increase our understanding of these issues related to health systems, AHRQ invested in the Comparative Health System Performance initiative to examine how systems might promote more patient-centered and higher-value care. As AHRQ’s Coordinating Center for this initiative, Mathematica developed a set of data resources called the AHRQ Compendium of U.S. Health Systems, the first publicly available data set to identify and classify all U.S. hospitals and medical groups that are members of health systems. The data resources in the Compendium identify more than 600 health systems (which combined deliver the substantial majority of care in the United States), linking these systems to many thousands of hospitals and physician practices in communities across the country. Mathematica also collaborated with AHRQ to analyze these data, which showed, among other insights, that in 2018, 72 percent of hospitals and 91 percent of hospital beds were in health systems. In addition, the percentage of physicians affiliated with health systems increased from 40 percent in 2016 to 51 percent in 2018 nationwide, and the percentage affiliated with health systems increased in nearly every metropolitan area during this two-year period.

These analyses confirm the substantial growth in the size and scope of health care systems. Three recent research briefs by Mathematica and AHRQ, summarized below, expand on the reach of health systems and their role in the delivery and financing of health care and highlight that the social benefits of this health system growth remain unclear.  

Employment of nurse practitioners and physician assistants in health systems suggests a greater focus on specialty care than primary care.
Advanced practice clinicians such as nurse practitioners (NPs) and physician assistants (PAs) are important resources for expanding access to primary care, a critical U.S. need. NPs and PAs can, however, also support the delivery of highly specialized care. We found that by 2018, 40 percent of NPs and PAs were employed in practice settings affiliated with a health system. We then explored the settings in which these clinicians provide care. Rates of system employment of NPs and PAs were highest in hospitals, multispecialty practice sites, and specialty practices associated with lucrative hospital services. System employment of NPs and PAs was lower in practice sites focused on primary care. These patterns are consistent with our findings on the integration of primary care and specialty physicians into health systems. Health systems appear to focus on integrating specialty services, which could limit their ability to expand access to primary care.

One-third of health systems offered their own health plan, which could have far-reaching implications for patients—but net impacts remain unclear.
A potential benefit of the growth of health systems is that the integration of providers and payers may motivate more efficient population-based care. Mathematica and AHRQ researchers studied new health plan information added to the 2018 Compendium and found that 34 percent of health systems offered at least one health plan. The percentage of systems offering Medicare Advantage, Medicaid managed care, large group, or small group plans was nearly 20 percent for each plan type. Larger systems and systems that covered a larger geographic area were substantially more likely than smaller systems to offer a health plan in at least one of their communities. But the share of patients covered by systems’ health plans is unknown. In addition, the degree to which disadvantaged patients benefit from enhanced financial access to care through these plans is unclear. Fewer systems that had a high burden of providing uncompensated care offered a plan relative to systems with a low burden. More research is needed to determine how health systems’ responsibility for delivery and cost of care will affect patients’ outcomes and health care spending.

More than half of system-affiliated physicians are participating in Medicare alternative payment models.
In addition to offering their own health plans, health systems can also choose to assume financial risk for more value-based care by participating in alternative payment models offered by the Centers for Medicare & Medicaid Services (CMS). Mathematica and AHRQ researchers found that, among physicians serving Medicare beneficiaries in 2018, 56 percent of health system-affiliated physicians participated in at least one Medicare alternative payment model, compared with only 33 percent of physicians not affiliated with a health system. Two-thirds of U.S. health systems had some physician participation in at least one Medicare alternative payment model, with 58 percent of these participating in a Medicare accountable care organization. Other research has suggested that within Medicare accountable care organizations, system-controlled physician practices have been less successful than independent physician practices at achieving higher-value care for Medicare beneficiaries. In contrast, a previous Mathematica and AHRQ analysis using the 2016 Compendium showed that, for specific hospital-based episodes of care, integration of relevant physicians may add value. The recent alternative payment model analysis, however, shows that less than 20 percent of systems that participate in CMS models focus on better management of specific episodes of care.

These research briefs illustrate how researchers can use the Compendium to uncover insights about health systems and understand how individual systems serve local communities. They also show how AHRQ has helped link publicly available Compendium data resources with other information that enables greater understanding through analysis of health systems. Because of the important and growing role of these systems, not just nationally but across local communities, policymakers and health care leaders must continue monitoring their development. Based on current evidence, the promise of health systems to improve care and reduce costs through better communication; coordinated, evidence-based practices; and improved efficiency has yet to be realized. Nonetheless, some of the analyses described here point to how these health care systems could promote higher-value care. Tools such as the AHRQ Compendium of U.S. Health Systems, especially when linked with other data sources, can provide insight into whether and how health systems can help overcome challenges regarding the cost and quality of care in the United States.

About the Authors

Michael F. Furukawa

Michael F. Furukawa

Director, Division of Healthcare Delivery and Systems Research, Center for Evidence and Practice Improvement, Agency for Healthcare Research and Quality
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