The U.S. Health Care Delivery Initiative (HCDI) has funded randomized evaluations across the United States. Read more about our funded projects below.
The Determinants of Health Insurance Take-up and Plan Choice in Covered California
Researcher: Wes Yin
While the Affordable Care Act aimed to expand insurance coverage in the United States, insurance take-up rates remain fairly low, and many individuals purchase plans that are sub-optimal for their needs. The success of the health insurance exchanges created by the ACA largely depends on the choices consumers make, but the underlying factors contributing to those choices are not well understood. This project will conduct a randomized evaluation in California to study the key determinants of health insurance take-up and plan choice. The study will evaluate how providing information about the benefits of purchasing a plan, premium subsidies, penalties of remaining uninsured, and making plans more easily comparable, affects insurance take-up and choice of plans.
The Effect of Behavioral Interventions on Enrollment and Adverse Selection in Health Insurance Marketplaces
Researchers: Timothy Layton, Keith Ericson, Adam Sacarny
Incomplete take-up of free and low-cost health insurance remains a puzzle. Failure to enroll in coverage has consequences for the uninsured as well as the health care providers and state budgets that bear the costs of uncompensated care. Moreover, if the marginal enrollee is healthier on average, increasing enrollment may improve competition and reduce premiums in the market by improving the risk pool. Research from other contexts suggests that behavioral frictions or mistakes may play an important role in determining whether households complete the enrollment process. Researchers will conduct a randomized trial to test “nudges” (letters sent by postal mail) that could increase enrollment in the Massachusetts Health Connector, the state marketplace through which eligible residents can obtain subsidized private coverage. Nudges will target households that were determined eligible for financial assistance but—for unknown reasons—failed to enroll in an insurance plan. Researchers will employ three treatment arms: a generic reminder letter, a personalized reminder letter, and a personalized reminder letter with a simplified (check-the-box) enrollment option. This will allow researchers to determine the mechanisms by which these nudges are (or aren’t) effective at (1) inducing enrollment among uninsured consumers and (2) shifting the risk pool.
Intervening with Consumers to Improve Choices on Health Insurance Marketplaces
Researchers: Keith Ericson, Jon Kingsdale, Timothy Layton, Adam Sacarny
The Affordable Care Act dramatically expanded the use of regulated marketplaces to provide individuals with health insurance coverage. The efficiency of these marketplaces depends on the ability of consumers to choose plans that reflect their preferences, but inattention and information frictions may inhibit optimal choices. In this project, researchers will conduct a randomized intervention to test the effect of sending information about the potential to switch plans and save on insurance premiums. Researchers will provide one random subset of re-enrolling individuals in Colorado's health insurance marketplace, Connect for Health Colorado, with personalized information about potential savings in two letters and two e-mails. They will send another random subset of re-enrolling individuals generic information about potential savings in two letters and two e-mails. Researchers will test the effect of these interventions on whether an individual switches her plan, the amount of her plan premium, and the breadth of her plan provider network. Researchers will also estimate the effect of the information on elasticities with respect to plan premiums and provider networks. The results of this study will shed light on behavioral frictions in health insurance and economic parameters central to market design. The study will also provide evidence on inexpensive, effective strategies for marketplaces and policymakers to improve consumers’ decision-making in selecting health plans.
Leveraging the Random Assignment of Medicaid Managed Care Plans to Study Plan Choices, Treatment Effects, and Cream Skimming
Researchers: Matt Notowidigdo, Craig Garthwaite
Location: South Carolina
In South Carolina, the Medicaid program is administered through Managed Care Organizations (MCOs), which offer different health care plans to Medicaid beneficiaries. These plans differ in their generosity, network coverage, and other attributes, and they are ranked by the state using a system of “star ratings.” The system of MCOs offers choices to health care consumers and allows plans to compete for consumers. In South Carolina, when consumers do not make an active plan choice, the state uses an algorithm to assign plans to consumers automatically. Starting in 2017, this auto-assignment will be made using an explicitly random process. Researchers will use this assignment feature to study the effect of plan assignment on patient outcomes such as health care utilization and expenditures. This prospective analysis will be complemented with a retrospective analysis that takes advantage of the state’s existing quasi-random round-robin assignment procedure to allocate households to plans. Additionally, researchers will combine the analysis of the randomly or quasi-randomly assigned population with the population that made active choices to try to distinguish between treatment and selection in accounting for which plans perform better.
Substance Use Disorders & Prescribing Behavior
Encouraging Abstinence Behavior in an Opioid Epidemic: Incentivizing Inputs and Outcomes
Researchers: Rebecca Dizon-Ross, Ariel Zucker
Location: United States
Combating the rise of the opioid epidemic is a central challenge of U.S. health care policy. A promising approach for improving welfare and decreasing medical costs of people with substance use disorders is offering incentive payments for healthy behaviors. This approach, broadly known as “contingency management” in the medical literature, has repeatedly shown to be effective in treating substance abuse. However, the use of incentives by treatment facilities remains extremely low. Furthermore, it is not well understood how to design optimal incentives to treat opioid abuse. This project will conduct a randomized evaluation of two incentive schemes for people with opioid use disorders, one incentivizing “inputs” to abstinence, and one incentivizing the “outcome” of abstinence. Both schemes are implemented with a novel “turnkey” mobile application, making them uniquely low-cost, low-hassle, and scalable. Effects will be measured on abstinence outcomes, including longest duration of abstinence and the percentage of negative drug tests, and the persistence of the effects will be assessed. In combination with survey data, variation from the experiment will shed light on the barriers to abstinence more broadly and inform our understanding of optimal incentive design.
Commit to Quit: Commitment Contracts for Smoking Cessation
Researchers: Jonathan Zinman, Dean Karlan, Samantha Horn
Location: Chicago, Illinois
This study will examine how advance commitment to a commitment contract impacts smoking cessation rates, by affecting the likelihood of taking up a commitment contract. By shifting the decision to start a commitment contract into an earlier time period, the option of pre-commitment negates the effect that present bias can have on the decision to commit in the moment. Thus, we expect that pre-commitment will increase the likelihood of an individual agreeing to a contract in the future, thereby increasing quit rates. We will recruit smokers from a general population in the Chicago metropolitan area and randomly assign respondents to one of four groups: a control group, a treatment group offered a deposit contract (a form of commitment contract) for smoking cessation, a second treatment group offered the option to pre-commit, a month in advance, to a deposit contract for smoking cessation, or a fourth group offered a deposit contract, and then if the offer is declined, offered the option to pre-commit. Further, we will provide causal evidence on how awareness that commitment contracts can assist with smoking cessation affects demand for commitment contracts. Deposit recovery for the treatment groups will be conditional on biochemical verification of self-reported smoking cessation. The primary outcomes of interest will be long-term cessation, measured 6 months after the interventions end. A short baseline and endline survey will also be administered to measure characteristics and outcomes related to smoking behavior.
Reducing Inappropriate Prescribing of Controlled Substances in the United States
Researchers: Adam Sacarny, David Yokum, Amy Finkelstein, Shantanu Agrawal
Location: United States
Inappropriate prescriptions are a rising threat to the health of patients, particularly senior citizens. Overprescription can also increase health care expenditures due to the direct cost of the drugs and the resulting health care use caused by adverse outcomes. This randomized evaluation studies a low-cost, light-touch intervention aimed at reducing the inappropriate provision of Schedule II controlled substances, which carry particularly large risks for patients, in the Medicare Part D program. Potential overprescribers were sent a letter explaining that their practice patterns were highly unlike those of their peers. Using rich administrative data to measure outcomes, researchers found no evidence that the letters had an impact on prescribing rates. The results of this study and further learning about the potential of light-touch interventions will help produce a better toolkit for policymakers to improve the value and safety of health care.
The Effect of Informative Letters on the Prescription and Receipt of Seroquel
Researchers: Adam Sacarny, David Yokum, Shantanu Agrawal
Location: United States
Abusive prescribing exposes patients to unnecessary health risks and results in wasteful public expenditures. This study will evaluate an innovative approach to fighting abusive prescription: sending letters to suspected inappropriate prescribers warning them that they are outliers compared to their peers and have been flagged for review. The study will target high prescribers of Seroquel (Quetiapine), a commonly prescribed antipsychotic. Using claims data, the researchers will assess the effect of the letters on prescribing of Seroquel, receipt of Seroquel by patients, substitution behavior by prescribers and patients, and health outcomes of patients.
PILOT: Pain Management Options for Opioid-Tolerant Patients: A Randomized Controlled Trial
Researchers: Joseph Doyle, Padma Gulur, Mireille Jacobson
Locations: California, North Carolina
Pain is a fundamental symptom that drives healthcare use, including hospital readmissions and patients who are on high levels of opioids have particularly high utilization patterns, including hospital admissions and emergency department visits. Pain specialists may be able to improve these patients’ health and reduce healthcare costs. While pain management is actively studied for acute episodes, and for chronic-pain patients, sub-acute patients leaving the hospital after surgery have received relatively little prior research. Researchers are conducting a randomized evaluation of a new clinical pathway developed to provide pain management to these patients throughout the acute and into the sub-acute phases. The pathway includes a consultation in the hospital by a team of pain management specialists. Patients will have access to these specialists during the sub-acute phase after discharge. Improved pain management holds the potential to break the cycle of readmissions and escalating opioid use among these high-risk, high resource utilizing patients. In addition, the study provides a model of how to roll out care re-designs via random assignment to study their effectiveness in a rigorous way.
PILOT: A Community Health Center Buyback Program to Reduce the Supply of Opioids to Secondary Users
Researchers: Alicia Sasser Modestino, Gary Young, Md Noor-E-Alam
Secure disposal of unused medications is one strategy to reduce the availability of opioids for diversion or abuse to secondary users after they have been dispensed. Are patients more likely to return unused opioids when informed and incentivized about a medication disposal program compared to passively observing a disposal kiosk in their pharmacy? We hypothesize that informing patients at the point of dispensing the medication, sending reminders via text message, and providing a financial incentive can significantly boost return rates. Our proposed pilot intervention will take place at five in-house pharmacies owned by a community health center yielding a potential sample size of 2,400 acute opioid prescriptions over 12 months that will be randomized across treatment and control groups. We will measure the percent of patients returning opioids as well as the amount and type of medication returned across both groups. We will also compare the amount returned to the amount prescribed by type of medication to better understand whether the program has an impact on usage and refills. Finally, we will explore the degree of heterogeneity in outcomes across different groups according to patient characteristics that predict opioid addiction such as age, gender, and diagnosis.
The Impact of Employee Wellness Programs: A Randomized Controlled Trial
Researchers: Katherine Baicker, Zirui Song
Location: United States
There is great public and private interest in the use of employee wellness programs to improve health and lower health care costs, with such programs promoted in the Affordable Care Act and adopted by half of large firms. However, little rigorous evidence exists on the effects of such programs. Using a randomized controlled design, the researchers propose to evaluate a year-long wellness intervention at BJ’s Wholesale Club, a large multi-state U.S. business with 201 sites (clubs) and over 25,000 employees. The wellness intervention will consist of several components, including team-based wellness challenges, nutrition counseling, stress reduction, and physical activity. The intervention has been designed with and will be fielded through Wellness Workdays, an experienced and large-scale vendor. Randomizing this intervention across a set of treatment clubs and control clubs, researchers will evaluate its impact on five categories of outcomes gathered from both primary and administrative data sources: (1) self-reported health and well-being, (2) biometrics (such as body mass index, blood pressure, blood sugar, etc.), (3) worker absenteeism and turnover, (4) health care spending and utilization, and (5) the implied return on investment. Better information about the effectiveness of such programs should inform both employer investment and public policy.
Worksite Wellness: A Field Experiment on Participation Incentives and Selection into Wellness Programs
Researchers: Damon Jones, David Molitor, and Julian Reif
Workplace wellness programs have become a $6 billion industry and are widely touted as a way to improve employee well-being, reduce health care costs by promoting prevention, and increase workplace productivity. Yet, there is little rigorous evidence available to support these claims, partly because the voluntary nature of these programs mean that participants may differ from nonparticipants for reasons unrelated to the causal effects of the wellness program. Researchers will implement a randomized control trial with the aim of answering three questions: (1) how do incentives affect the level of participation in wellness programs; (2) what types of workers select into wellness programs, and how do incentives affect that composition; and (3) what is the causal impact of worksite wellness participation on health, health care costs, and productivity?
Maternal and Child Health
PILOT: Contraceptive counseling for postpartum moms during pediatric visits
Researchers: Jessica Cohen and Margaret McConnell
Researchers are conducting a pilot study in collaboration with University of Kansas Pediatric Clinic to prepare for a large-scale trial examining the impact of contraceptive counseling for moms at their infants’ pediatric visits on postpartum contraceptive use. Over half of all pregnancies in the United States are unplanned, with a substantial share occurring after insufficient spacing between pregnancies, contributing to morbidity and mortality risk for mothers and babies. The researchers hypothesize that many postpartum women have insufficient contact with providers who traditionally counsel on family planning, but that these moms are in frequent contact with the medical system through their infants’ pediatrician visits, which provide repeat opportunities for contraceptive counseling and follow-up. The objectives of the pilot study are to collect baseline data to identify a key target population and conduct a sample size calculation, assess the acceptability of the proposed intervention, develop protocols and data collections systems, and to identify potential complementary interventions to increase the implementation and impact of the program. The findings of this pilot will be used to design a full-scale effectiveness trial assessing program impact on postpartum contraceptive use.
Improving the Outcomes of SSI Children through Information
Researchers: Manasi Deshpande, Rebecca Dizon-Ross
Location: United States
Supplemental Security Income (SSI) provides cash payments to the families of 1.3 million low-income disabled children who are at risk for poor life outcomes. Available evidence indicates that many SSI families are unaware of the likelihood that children will be removed from SSI at age 18, and may therefore underinvest in the human capital of their children. In this randomized evaluation, researchers will collaborate with state vocational rehabilitation agencies to estimate the effects of providing SSI youth and their families with information about the likelihood of removal from SSI at age 18. Researchers will estimate the effects of written information and information-driven counseling about SSI removal on the educational, health, employment, and justice-involvement outcomes of the SSI youth.
Randomized Evaluation of the Nurse-Family Partnership
Researchers: Katherine Baicker, Mary Ann Bates, Margaret McConnell, Michelle Woodford, Annetta Zhou
Location: South Carolina
There is enormous policy interest in expanding programs that move beyond traditional health care walls into the community to improve health outcomes – and holding those programs financially responsible for doing so. Billions of public dollars are devoted to “home visiting” programs that seek to improve birth and long-term outcomes for low-income mothers and children. The Nurse-Family Partnership (NFP) program provides regular nurse home visits to low-income, first-time mothers through pregnancy and up to the first two years postpartum in order to improve the outcomes of both mothers and their children. South Carolina obtained a Medicaid waiver and generous philanthropic support to fund a landmark pay-for-success initiative that expanded NFP’s services across the state. This randomized evaluation will assess a number of “success indicators” relevant to the pay-for-success initiative, such as the program’s effectiveness in reducing injuries among newborns and toddlers, as well as study the potentially wide-ranging effects of NFP on the health and well-being of mothers and children for many years to come. The study aims to yield insights into the effectiveness of home visiting programs, the sustainability of more flexible public insurance benefits, and the potential role that evidence-based payments can play in driving improved outcomes.
PILOT: Overcoming Financial Barriers to Caring for Preterm Infants
Researchers: Guenther Fink, Margaret McConnell
This pilot randomized controlled trial, conducted in collaboration with Tufts Medical Center, aims to determine whether financial support can increase caregivers’ ability to breastfeed and provide skin-to-skin care to preterm infants. The study team's central hypothesis is that low-income households cannot afford to spend extended periods of time in the hospital after preterm delivery, which makes both exclusive breastfeeding and continued skin-to-skin care – two highly effective practices to improve preterm health – very difficult. The objective of the pilot study is to develop a protocol for a financial support system targeted to low-income mothers with babies in neonatal intensive care units (NICUs). The primary outcomes of the pilot trial will be breastfeeding initiation and continuation and the number of hours of skin-to-skin care provided to the infant. Estimates of the impact of financial transfers on these outcomes will be of critical importance to power a larger subsequent effectiveness trial assessing program impact on key child health outcomes.
PILOT: Planning a Randomized Evaluation of the Effects of No-Cost Long-Acting Reversible Contraception on Education and Employment Outcomes
Researchers: Marianne Bertrand, David Meltzer, Harold Pollack
Long-Acting Reversible Contraception (LARC) is highly effective at preventing unplanned pregnancy, but the cost of LARCs drives down uptake among low-income populations. Past research has linked unplanned pregnancy among female teens to adverse educational and labor market outcomes. However, no research to date has shown how access to, and uptake of, LARCs might help improve these outcomes for women. Planned Parenthood of Illinois (PPIL) offers abortion and contraception services to clients, and recently launched an initiative to reduce financial barriers to contraceptive access. Coinvestigators Marianne Bertrand, Harold Pollack and David Meltzer propose to conduct a randomized controlled trial of this program, comparing unplanned pregnancy, education, and employment outcomes of eligible patients randomly assigned to receive treatment to those of a control group. This pilot project will allow the project team to plan and prepare for the RCT, which will provide valuable insights not only to PPIL, but also to other providers and policy makers working to understand the far reaching effects of no-cost LARC delivery on other societal outcome
Reducing Economic & Racial Disparities
Health Care Hotspotting: A Randomized Controlled Trial
Researchers: Jeffrey Brenner, Joseph Doyle, Amy Finkelstein, Sarah Taubman, R. Annetta Zhou
Location: Camden, New Jersey
The Camden Coalition of Healthcare Providers’ Care Management Program, Link2Care, targets “super-utilizers” of the health care system – specifically adults with two or more hospitalizations in the prior six months and multiple chronic conditions – with intensive care-management services in the months following hospital discharge. A team of nurses, social workers, community health workers, and health coaches, supported by real-time data of health care use, perform home visits, accompany patients to doctor visits, and help patients enroll in social-service programs. This approach aims to improve the self-sufficiency of patients in navigating the health care and social-service systems and has the potential to reduce hospital re-admissions and improve patient well-being. This project will rigorously investigate the impacts of the program on subsequent health care utilization and the use of social services through a randomized controlled trial.
A Randomized Trial to Identify the Effects of Provider Race on the Health Behavior of Black Men
Researcher: Marcella Alsan
Location: Oakland, California
Reducing racial disparities in health outcomes is a major policy concern in the United States. Although there has been recent progress to close the gap, black men continue to experience earlier morbidity and mortality from preventable and manageable medical conditions, and live on average 4.5 years less than their white male peers. An oft-prescribed solution to close this stubborn gap is to increase the diversity of the healthcare workforce. Another common policy tool to increase take-up of preventative healthcare services are subsidies. In this randomized evaluation, the research team will estimate the effects of subsidies and a racially concordant physician on the uptake of preventive health services in Oakland, California.
The Burden of Medical Debt and the Impact of Debt Forgiveness
Researchers: Neale Mahoney, Raymond Kluender, Francis Wong, Wesley Yin
Location: United States
Medical debt is potentially a large burden for many Americans—with 44 million individuals holding an aggregate $75 billion in medical debt. While these nominal amounts are staggering, it is unclear to what extent medical debt harms financial well-being. Medical debt recovery rates are low, suggesting that the pure “balance sheet” cost of medical debt is modest for most individuals. Yet medical debt may harm individuals through lower credit scores, higher interest rates, and reduced access to credit—impairing economic opportunities and perhaps even locking individuals in “debt traps.” Collaborating with RIP Medical Debt, a non-profit that buys and abolishes medical debt, researchers will implement a randomized-control trial to study the impact of medical debt. Medical debt will be forgiven for randomly chosen “treated” individuals, whose financial outcomes will be compared to otherwise similar “control” individuals for whom medical debt will not be forgiven.
PILOT: Nutritional Supports for At‐Risk Patients
Researchers: Seth Berkowitz, Joseph Doyle, Amy Finkelstein
Cardiovascular diseases are by far the leading causes of death in the U.S., with over 800,000 deaths annually. Approximately 1 in 4 Americans with cardiometabolic conditions such as hypertension, hyperlipidemia, and diabetes experience food insecurity, which is suspected to be a major, modifiable risk factor for these health conditions. This pilot study seeks to determine the feasibility of a randomized evaluation of two interventions targeting the diets of low-income patients at high risk of cardiovascular disease: (1) helping patients enroll in the Supplemental Nutrition Assistance Program (SNAP) and (2) providing medically‐tailored meals directly to patients.
Cost-Effectiveness, Quality, & Spending
PILOT: Deferring Agency at End-of-Life: The Role of Information and Advance Directives
Researchers: Ben Handel, Allyson Barnett Root
Location: Oregon and Washington
Researchers will pilot a randomized evaluation of strategies to facilitate advance directive completion in the over-65 patient population of Providence St. Joseph Health. Despite the significant economic and personal implications of end-of-life health care decisions, many fail to document their wishes or to select a representative who can make medical decisions on their behalf. Descriptive evidence suggests that this results in sub-optimal outcomes including dissatisfaction and potentially unnecessary medical spending. However, it is not well understood why patients fail to engage in this apparently high-value planning. The trial will pilot two interventions with roughly 1000 patients, with intention to scale the evaluation to include over 70,000 patients across 64 clinics. Researchers will evaluate the effects of (i) an in-person drive to facilitate advance directive completion, (ii) an informational video on advance directives that will be electronically distributed to patients, and (iii) the interaction of these two interventions. Key outcomes will include advance directive completion rates, decisions made on advance directive forms, and eventually observed care decisions. Researchers will also leverage surveys and granular data on patient health to better understand barriers to advance care planning and relate to underlying economic theory that explains behavior.
PILOT: Do Informed Physicians Make Better Referrals?
Researchers: Zack Cooper, Michael Chernew, Fiona Scott Morton
Location: United States
Health care providers’ prices vary substantially within geographies and there is little evidence that higher priced providers deliver higher quality care. With more than 43% of total health care spending estimated to be ‘shoppable’, the savings from improving how patients navigate the health system could be substantial. Indeed, using claims data from a large commercial insurer, the researchers have identified that, if every patient who received an MRI in 2014 at a provider with prices above the 25th percentile had gone to a provider at the 25th percentile price, it would have resulted in a 41% decrease in MRI spending. The researchers will use a clustered RCT to test the effect of providing referring physicians – patients’ agents – with pricing information on where they send their patients for care and financial incentives to steer their patients towards more efficient providers. This project will test whether equipping providers with information on the price of their referrals during the care process leads to reductions in the price of imaging services received by their patients.
PILOT: Financial Incentives to Increase Health System Engagement Among Those with Complex Needs
Researchers: Marika Cabral, Rebecca Dizon-Ross, Caterina Hill, Zirui Song
Financial incentives to encourage patient engagement have been found to be useful in other settings, but have not been adequately tested with complex needs populations. In collaboration with the Commonwealth Care Alliance, researchers will pilot a randomized controlled trial to test whether small financial incentives will increase beneficiary engagement in primary care amongst individuals dually eligible for Medicare and Medicaid. The pilot will randomize financial incentives for engagement in primary care among newly enrolled CCA beneficiaries. In a later, full RCT, researchers plan to investigate the impact of financial incentives for increased primary care engagement on additional outcomes, such as the receipt of clinically effective prevention services and utilization.
PILOT: Mobile-izing Medicine: The Effect of Accessible Clinical Practice Guidelines on the Quality of Hospital Care
Researchers: Zarek Brot-Goldberg, Benjamin Handel, Jonathan Kolstad, Michael Whinston
Lack of adherence to clinical practice guidelines is an important source of preventable medical errors. Nevertheless, lack of adherence to such guidelines, and clinical error more generally, is widespread in health care delivery today. One potential barrier to adherence is the fact that these guidelines are typically inaccessible at the point of care, precisely when they are most needed. The expansion of IT systems (e.g. electronic health records) in health care settings, as well as the propagation of mobile devices, has created a plausible way to overcome this barrier. In this study, researchers assess the impact of electronic access to practice guidelines to improve care, using the case of a mobile-based application called AgileMD. To do so, researchers assess adoption of the tool, use of the tool and, ultimately, clinical outcomes. Using detailed data and quasi-random variation, results from these analyses will lay the groundwork for a randomized controlled trial of the AgileMD tool.
The Impact of Medicare Bundled Payments: Evidence from a Nationwide Randomized Evaluation for Lower Extremity Joint Replacement
Researchers: Amy Finkelstein, Yunan Ji, Neale Mahoney, Jonathan Skinner
Location: United States
Bundled payments are a key part of Medicare’s shift away from the traditional fee-for-service (FFS) payment model. We propose to study a nationwide randomized-controlled trial (RCT) of bundled payments for knee and hip replacements that was designed by CMS and launched in April 2016. Randomization was conducted at the Metropolitan Statistical Area (MSA) level with 67 MSAs and more than 800 hospitals assigned to the treatment group. We will examine the impact of bundled payments on Medicare spending, utilization, and quality. Our findings should be directly relevant for the design of payments for knee and hip replacements, two common and expensive medical procedures. Average impacts, as well as variation in impact across types of providers and markets may also shed light on economic mechanisms, which should be relevant for bundled payment initiatives under consideration for other medical services. System-wide policies such as payment reform are typically held up as a prime example of an environment where RCTs are impractical. Our study and its results will highlight the feasibility and value of such RCTs.