Research

Working Paper
Yunan Ji. Working Paper. “Can Competitive Bidding Work in Health Care? Evidence from Medicare Durable Medical Equipment.”. Link to PaperAbstract

Prices are a significant driver of high health care spending in the US, but how to reduce prices remains an open question. I examine one widely-touted solution – setting prices via competitive bidding – in the context of a Medicare payment reform. The reform gradually replaced administratively-set prices with prices from competitive bidding for durable medical equipment (DME) in 100 metropolitan statistical areas. Using detailed claim-level data, I estimate that the competitive bidding program reduced the prices of covered items by 45%. However, the program also generated an 11% reduction in quantity, which several pieces of evidence suggest is associated with inefficient supply shortages. One likely cause of the shortage is the auction design, which allows winning bidders to renege on supply commitment. Leveraging novel bid data, I estimate an equilibrium model of optimal bidding and find that the program generated prices that were on average 6% below the market clearing price, consistent with the observed supply shortages. I use the results to show that counterfactual auction designs could reach the desired market quantity while saving 43% in government spending relative to administratively-set prices. The analysis highlights the importance of auction design in achieving desirable outcomes, and suggests that a well-designed competitive bidding program could potentially generate large savings in health care.

Job Market Paper

Journal Article
Liran Einav, Amy Finkelstein, Yunan Ji, and Neale Mahoney. Forthcoming. “Voluntary Regulation: Evidence from Medicare Payment Reform.” Quarterly Journal of Economics. Link to PaperAbstract
Government programs are often offered on an optional basis to market participants. We explore the economics of such voluntary regulation in the context of a Medicare payment reform, in which one medical provider receives a single, predetermined payment for a sequence of related healthcare services, instead of separate service-specific payments. This “bundled payment” program was originally implemented as a 5-year randomized trial, with mandatory participation by hospitals assigned to the new payment model; however, after two years, participation was made voluntary for half of these hospitals. Using detailed claim-level data, we document that voluntary participation is more likely for hospitals that can increase revenue without changing behavior (“selection on levels”) and for hospitals that had large changes in behavior when participation was mandatory (“selection on slopes”). To assess outcomes under counterfactual regimes, we estimate a stylized model of responsiveness to and selection into the program. We find that the current voluntary regime generates inefficient transfers to hospitals, and that alternative (feasible) designs could reduce these inefficient transfers and raise welfare. Our analysis highlights key design elements to consider under voluntary regulation.
Liran Einav, Amy Finkelstein, Yunan Ji, and Neale Mahoney. 7/27/2020. “Randomized trial shows healthcare payment reform has equal-sized spillover effects on patients not targeted by reform.” Proceedings of the National Academy of Sciences of the United States of America. Publisher's VersionAbstract
Changes in the way health insurers pay healthcare providers may not only directly affect the insurer’s patients but may also affect patients covered by other insurers. We provide evidence of such spillovers in the context of a nationwide Medicare bundled payment reform that was implemented in some areas of the country but not in others, via random assignment. We estimate that the payment reform—which targeted traditional Medicare patients—had effects of similar magnitude on the healthcare experience of nontargeted, privately insured Medicare Advantage patients. We discuss the implications of these findings for estimates of the impact of healthcare payment reforms and more generally for the design of healthcare policy.
  • Summary of study on J-PAL
Zirui Song, Yunan Ji, Dana Safran, and Michael Chernew. 7/18/2019. “Health Care Spending, Utilization, and Quality 8 Years into Global Payment.” New England Journal of Medicine, 381, Pp. 252-263. Publisher's VersionAbstract

Background Population-based global payment gives health care providers a spending target for the care of a defined group of patients. We examined changes in spending, utilization, and quality through 8 years of the Alternative Quality Contract (AQC) of Blue Cross Blue Shield (BCBS) of Massachusetts, a population-based payment model that includes financial rewards and penalties (two-sided risk).

Methods Using a difference-in-differences method to analyze data from 2006 through 2016, we compared spending among enrollees whose physician organizations entered the AQC starting in 2009 with spending among privately insured enrollees in control states. We examined quantities of sentinel services using an analogous approach. We then compared process and outcome quality measures with averages in New England and the United States.

Results During the 8-year post-intervention period from 2009 to 2016, the increase in the average annual medical spending on claims for the enrollees in organizations that entered the AQC in 2009 was $461 lower per enrollee than spending in the control states (P<0.001), an 11.7% relative savings on claims. Savings on claims were driven in the early years by lower prices and in the later years by lower utilization of services, including use of laboratory testing, certain imaging tests, and emergency department visits. Most quality measures of processes and outcomes improved more in the AQC cohorts than they did in New England and the nation in unadjusted analyses. Savings were generally larger among subpopulations that were enrolled longer. Enrollees of organizations that entered the AQC in 2010, 2011, and 2012 had medical claims savings of 11.9%, 6.9%, and 2.3%, respectively, by 2016. The savings for the 2012 cohort were statistically less precise than those for the other cohorts. In the later years of the initial AQC cohorts and across the years of the later-entry cohorts, the savings on claims exceeded incentive payments, which included quality bonuses and providers’ share of the savings below spending targets.

Conclusion During the first 8 years after its introduction, the BCBS population-based payment model was associated with slower growth in medical spending on claims, resulting in savings that over time began to exceed incentive payments. Unadjusted measures of quality under this model were higher than or similar to average regional and national quality measures. (Funded by the National Institutes of Health.)

Amy Finkelstein, Yunan Ji, Neale Mahoney, and Jonathan Skinner. 9/4/2018. “Mandatory Medicare Bundled Payment Program for Lower Extremity Joint Replacement and Discharge to Institutional Postacute CareInterim Analysis of the First Year of a 5-Year Randomized Trial.” Journal of the American Medical Association. Publisher's VersionAbstract

Importance  Bundled payments are an increasingly common alternative payment model for Medicare, yet there is limited evidence regarding their effectiveness.

Objective  To report interim outcomes from the first year of implementation of a bundled payment model for lower extremity joint replacement (LEJR).

Design, Setting, and Participants  As part of a 5-year, mandatory-participation randomized trial by the Centers for Medicare & Medicaid Services, eligible metropolitan statistical areas (MSAs) were randomized to the Comprehensive Care for Joint Replacement (CJR) bundled payment model for LEJR episodes or to a control group. In the first performance year, hospitals received bonus payments if Medicare spending for LEJR episodes was below the target price and hospitals met quality standards. This interim analysis reports first-year data on LEJR episodes starting April 1, 2016, with data collection through December 31, 2016.

Exposure  Randomization of MSAs into the CJR bundled payment model group (75 assigned; 67 included) or to the control group without the CJR model (121 assigned; 121 included). Instrumental variable analysis was used to evaluate the relationship between inclusion of MSAs in the CJR model and outcomes.

Main Outcomes and Measures  The primary outcome was share of LEJR admissions discharged to institutional postacute care. Secondary outcomes included the number of days in institutional postacute care, discharges to other locations, Medicare spending during the episode (overall and for institutional postacute care), net Medicare spending during the episode, LEJR patient volume and patient case mix, and quality-of-care measures.

Results  Among the 196 MSAs and 1633 hospitals, 131 285 eligible LEJR procedures were performed during the study period (mean volume, 110 LEJR episodes per hospital) among 130 343 patients (mean age, 72.5 [SD, 0.91] years; 65% women; 90% white). The mean percentage of LEJR admissions discharged to institutional postacute care was 33.7% (SD, 11.2%) in the control group and was 2.9 percentage points lower (95% CI, −4.95 to −0.90 percentage points) in the CJR group. Mean Medicare spending for institutional postacute care per LEJR episode was $3871 (SD, $1394) in the control group and was $307 lower (95% CI, −$587 to −$27) in the CJR group. Mean overall Medicare spending per LEJR episode was $22 872 (SD, $3619) in the control group and was $453 lower (95% CI, −$909 to $3) in the CJR group, a statistically nonsignificant difference. None of the other secondary outcomes differed significantly between groups.

Conclusions and Relevance  In this interim analysis of the first year of the CJR bundled payment model for LEJR among Medicare beneficiaries, MSAs covered by CJR, compared with those that were not, had a significantly lower percentage of discharges to institutional postacute care but no significant difference in total Medicare spending per LEJR episode. Further evaluation is needed as the program is more fully implemented.

Tinting Fu, Yunan Ji, Kenju Kamei, and Louis Putterman. 5/2017. “Punishment can support cooperation even when punishable.” Economics Letters. Publisher's VersionAbstract
Do opportunities to punish non-punishers help to stabilize cooperation? Or do opportunities to punish punishers harm cooperation and its benefits by deterring first order punishment and wasting resources? We compare treatments of a decision experiment without peer punishment and with one order of punishment to ones in which subjects can be punished for punishing or for failing to punish. Our treatments with higher-order punishment achieve as much improvement in cooperation as those with only one punishment stage. We see evidence of social norms in action, but no evidence of punishing failure to punish. These results suggest that higher-order punishment is neither critical to nor a major deterrent to cooperation.