Purpose

The authors undertook a study to determine whether large academic and community-based medical groups differ in terms of their financial stake in Medicare Advantage or Medicare Accountable Care Organizations (ACOs) and whether their participation in these alternative payment models is related to their size, specialty mix, and Medicare physician market share in their local area.

Method

The authors used the 2013 Medicare Data on Provider Practice and Specialty database and a national database of ACOs to conduct a cross-sectional descriptive study of the 100 largest medical groups in the United States. Medical groups were categorized as academic or community based on matches of their name with a list of U.S. medical schools or the results of a series of Internet search procedures.

Results

Sixty-eight of the 100 largest groups were academic, and 32 were community based. On average, community-based groups had more than twice the percentage of primary care physicians as academic groups (mean, 38.4%; 95% CI, 34.7%-42.0%; vs. 18.3%; 95% CI, 17.0%-19.6%). Community groups were significantly (P < .001) more likely than academic groups to have a financial stake in a Medicare ACO or Medicare Advantage plan, but this difference was no longer significant when the percentage of primary care physicians in the group was added to the model.

Conclusions

The specialty mix within academic medical groups may hinder their ability to transform themselves into organizations that can manage the financial responsibilities of caring for a patient population through a Medicare ACO or Medicare Advantage.

Background

A growing proportion of Medicare beneficiaries is covered by private insurers through Medicare Advantage, yet little is known about how these plans are structured in terms of relationships with physicians and implications for quality of care.

Objective

The objective of this study was to assess whether greater physician concentration of services across insurers was associated with higher quality in Medicare Advantage (MA), overall and particularly among MA insurers serving a high proportion of vulnerable enrollees.

Research design

A retrospective cohort design with regression analysis.

Data sources

The primary dataset was 2014 MA encounter records submitted by insurers to the Centers for Medicare and Medicaid Services, covering 600,329 physicians across 119 insurers. These data were merged with Centers for Medicare and Medicaid Services data on MA contract quality rating as well as physician characteristics in the Medicare Data on Provider Practice and Specialty file.

Measures

Two measures were generated to capture the concentration of physician services across insurers: the percentage of a physician's Medicare services which was through MA (MA penetration); and the percentage of a physician's MA services with a specific insurer (insurer share of MA services).

Results

Greater MA penetration and insurer share of MA services were each associated with higher MA plan quality. The relationship between insurer share and quality was stronger in contracts with a relatively high percentage of disabled enrollees.

Conclusion

Greater physician concentration of services across MA insurers was associated with a higher quality of care overall and especially among vulnerable enrollees.

To describe the characteristics of hospitalists serving Medicare beneficiaries. Medicare claims from 2009 and 2011 merged with the Provider Enrollment, Chain, and Ownership System file for physician characteristics. Our construction of the Medicare Data on Physician Practice and Specialty (MD-PPAS) enabled identification of hospitalists based on the attending physician for Medicare admissions (medical and surgical) in 2009 and 2011. In 2011, hospitalists constituted 13.3% of physicians who designated their specialty as primary care and 4.4% of all physicians serving Medicare beneficiaries. Compared to other physicians, hospitalists were more likely to be female, under forty, and in large practices. More than a quarter of Medicare admissions had a hospitalist as the attending physician, though the rate was substantially higher for medical than surgical admissions (31.8% versus 11.3%). Between 2009 and 2011, the percentage of medical admissions with a hospitalist as the attending physician increased by roughly a quarter (from 25.7% to 31.8%). This analysis provides a more current and complete estimate of the use of hospitalists by the Medicare population than is available from prior studies. The ability to identify hospitalists from claims data will facilitate research on the impact of hospitalist use on quality and cost.

Payers and advocates for improved health care quality are raising expectations for greater care coordination and accountability for care delivery, and physician groups may be responding by becoming larger. We used Medicare claims from the period 2009-11, merged with information from the Medicare provider enrollment database, to measure whether physician group sizes have been increasing over time and in association with physician characteristics. All US physicians serving Medicare fee-for-service patients in any practice setting were included. The percentage of physicians in groups of more than fifty increased from 30.9 percent in 2009 to 35.6 percent in 2011. This shift occurred across all specialty categories, both sexes, and all age groups, although it was more prominent among physicians under age forty than those age sixty or older. The movement of physicians into groups is not a new phenomenon, but our data suggest that the groups are larger than surveys have previously indicated. Questions for future studies include whether there are significant cost savings or quality improvements associated with increased practice size.