J. Michael McWilliams
Harvard Medical School
Department of Health Care Policy
180 Longwood Avenue
Boston, MA 02115
Institutional Affiliation: Harvard Medical School
NBER Working Papers and Publications
|October 2019||Spending Reductions in the Medicare Shared Savings Program: Selection or Savings?|
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Evidence of patient and physician turnover in accountable care organizations (ACOs) has raised concerns that ACOs may be earning shared-savings bonuses by selecting for lower-risk patients or providers with lower-risk panels. We conducted three sets of analyses to examine risk selection in the Medicare Shared Savings Program. First, we estimated overall MSSP savings through 2015 using a difference-in-differences approach and methods that eliminated selection bias from ACO program exit or changes in the practices or physicians included in ACO contracts. We then checked for residual risk selection at the patient level. Second, we re-estimated savings with methods that address undetected risk selection but could introduce bias from other sources. These included patient fixed effects, baselin...
|February 2018||The Comparative Advantage of Medicare Advantage|
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We ascertain the degree of service-level selection in Medicare Advantage (MA) using individual level data on the 100 most frequent HCC’s or combination of HCC’s from two national insurers in 2012-2013. We find differences in the distribution of beneficiaries across HCC’s between TM and MA, principally in the smaller share of MA enrollees with no coded HCC, consistent with greater coding intensity in MA. Among those with an HCC code, absolute differences between MA and TM shares of beneficiaries are small, consistent with little service-level selection.
Variation in HCC margins does not predict differences between an HCC’s share of MA and TM enrollees, although one cannot a priori sign a relationship between margin and service-level selection. Margins are negatively associated with th...
Published: Joseph P. Newhouse & Mary Beth Landrum & Mary Price & J. Michael McWilliams & John Hsu & Thomas G. McGuire, 2019. "The Comparative Advantage of Medicare Advantage," American Journal of Health Economics, vol 5(2), pages 281-301. citation courtesy of
|March 2014||How Much Favorable Selection Is Left in Medicare Advantage?|
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There are two types of selection models in the health economics literature. One focuses on choice between a fixed set of contracts. Consumers with greater demand for medical care services prefer contracts with more generous reimbursement, resulting in a suboptimal proportion of consumers in such contracts in equilibrium. In extreme cases more generous contracts may disappear (the "death spiral"). In the other model insurers tailor the contracts they offer consumers to attract profitable consumers. An equilibrium may or may not exist in such models, but if it exists it is not first best.
The Medicare Advantage program offers an opportunity to study these models empirically, although unlike the models in the economics literature there is a regulator with various tools to address sele...
Published: Joseph P. Newhouse & Mary Price & John Hsu & J. Michael McWilliams & Thomas G. McGuire, 2015. "How Much Favorable Selection Is Left in Medicare Advantage?," American Journal of Health Economics, MIT Press, vol. 1(1), pages 1-26, Winter. citation courtesy of