Zack Cooper Publications

From 2002 to 2020, there were over 1,000 mergers of US hospitals. During this period, the Federal Trade Commission (FTC) took enforcement actions against 13 transactions. However, using the FTC’s standard screening tools, we find that 20% of these mergers could have been predicted to meaningfully lessen competition. We then show that, from 2010 to 2015, predictably anticompetitive mergers resulted in price increases over 5%. We estimate that approximately half of predictably anticompetitive mergers had to be reported to the FTC per the Hart-Scott-Rodino Act. We conclude that there appears to be underenforcement of antitrust laws in the hospital sector.

Review of the Expert and Academic Literature Assessing Impact of Medicare Access and CHIP Reauthorization Act of 2015

We analyze whether receiving care from higher-priced hospitals leads to lower mortality. We overcome selection issues by using an instrumental variable approach which exploits that ambulance companies are quasi-randomly assigned to transport patients and have strong preferences for certain hospitals. Being admitted to a hospital with two standard deviations higher prices raises spending by 52% and lowers mortality by 1 percentage point (35%). However, the relationship between higher prices and lower mortality is only present at hospitals in less concentrated markets. Receiving care from an expensive hospital in a concentrated market increases spending but has no detectable effect on mortality.

We study where privately insured individuals receive planned MRI scans. Despite significant out-of-pocket costs for this undifferentiated service, privately insured patients often  receive care in high-priced locations when lower priced options were available. The median patient in our data has 16 MRI providers within a 30-minute drive of her home. On average, patients bypass 6 lower-priced providers between their homes and their actual treatment locations. Referring physicians heavily influence where patients receive care. The share of the variance in the prices of patients’ MRI scans that referrer fixed effects (52 percent) explain is dramatically greater than the share explained by patient cost-sharing (< 1 percent), patient characteristics (< 1 percent), or patients’ home HRR fixed effects (2 percent). In order to access lower cost providers, patients must generally diverge from physicians’ established referral patterns.

We uncover political dynamics that reward and reinforce increases in US health spending by studying the passage of the 2003 Medicare Modernization (MMA). We focus on a provision added to the MMA, which allowed hospitals to apply for temporary Medicare payment increases. Hospitals represented by members of Congress who voted ‘Yea’ to the MMA were more likely to receive payment increases. The payment increases raised local health spending and led to suggestive increases in health sector employment. Members of Congress representing hospitals that got a payment increase received large increases in campaign contributions before and after the program was extended.

When physicians whom patients do not choose and cannot avoid can bill out of network for care delivered within in-network hospitals, it exposes patients to financial risk and undercuts the functioning of health care markets. Using data for 2015 from a large commercial insurer, we found that at in-network hospitals, 11.8 percent of anesthesiology care, 12.3 percent of care involving a pathologist,
5.6 percent of claims for radiologists, and 11.3 percent of cases involving an assistant surgeon were billed out of network. The ability to bill out of network allows these specialists to negotiate artificially high in-network rates. Out-of-network billing is more prevalent at hospitals in concentrated hospital and insurance markets and at for-profit hospitals. Our estimates show that if these specialists were not able to bill out of network, it would lower physician payments for privately insured patients by 13.4 percent and reduce health care spending for people with employer-sponsored insurance by 3.4 percent (approximately $40 billion annually).

We use insurance claims data covering 28% of individuals with employer-sponsored health insurance in the United States to study the variation in health spending on the privately insured, examine the structure of insurer-hospital contracts, and analyze the variation in hospital prices across the nation. Health spending per privately insured beneficiary differs by a factor of three across geographic areas and has a very low correlation with Medicare spending. For the privately insured, half of the spending variation is driven by price variation across regions, and half is driven by quantity variation. Prices vary substantially across regions, across hospitals within regions, and even within hospitals. For example, even for a nearly homogeneous service such as lower-limb magnetic resonance imaging, about a fifth of the total case-level price variation occurs within a hospital in the cross section. Hospital market structure is strongly associated with price levels and contract structure. Prices at monopoly hospitals are 12% higher than those in markets with four or more rivals. Monopoly hospitals also have contracts that load more risk on insurers (e.g., they have more cases with prices set as a share of their charges). In concentrated insurer markets the opposite occurs—hospitals have lower prices and bear more financial risk. Examining the 366 mergers and acquisitions that occurred between 2007 and 2011, we find that prices increased by over 6% when the merging hospitals were geographically close (e.g., 5 miles or less apart), but not when the hospitals were geographically distant (e.g., over 25 miles apart). JEL Codes: I11, L10, L11.

Evidence suggests that growth in providers’ prices drives growth in health care spending on the privately insured. However, existing work has not systematically differentiated between the growth rate of hospital prices and that of physician prices. We analyzed growth in both types of prices for inpatient and hospital-based outpatient services using actual negotiated prices paid by insurers.

We found that in the period 2007–14 hospital prices grew substantially faster than physician prices. For inpatient care, hospital prices grew 42 percent, while physician prices grew 18 percent. Similarly, for hospital-based outpatient care, hospital prices grew 25 percent, while physician prices grew 6 percent. A majority of the growth in payments for inpatient and hospital-based outpatient care was driven by growth in hospital prices, not physician prices.

Our work suggests that efforts to reduce health care spending should be primarily focused on addressing growth in hospital rather than physician prices. Policymakers should consider a range of options to address hospital price growth, including antitrust enforcement, administered pricing, the use of reference pricing, and incentivizing referring physicians to make more cost-efficient referrals.

We examined the growth in health spending on people with employer-sponsored private insurance in the period 2007–14. Our analysis relied on information from the Health Care Cost Institute data set, which includes insurance claims from Aetna, Humana, and UnitedHealthcare. In the study period private health spending per enrollee grew 16.9 percent, while growth in Medicare spending per fee-for-service beneficiary decreased 1.2 percent. There was substantial variation in private spending growth rates across hospital referral regions (HRRs): Spending in HRRs in the tenth percentile of private spending growth grew at 0.22 percent per year, while HRRs in the ninetieth percentile experienced 3.45 percent growth per year. The correlation between the growth in HRR-level private health spending and growth in fee-for-service Medicare spending in the study period was only 0.211. The low correlation across HRRs suggests that different factors may be driving the growth in spending on the two populations.

This paper examines the impact of a government programme which facilitated the entry of for-profit surgical centres to compete against incumbent National Health Service hospitals in England. We examine the impact of competition from these surgical centres on the efficiency – measured by pre-surgery length of stay for hip and knee replacement patients – and case mix of incumbent public hospitals. We exploit the fact that the government chose the broad locations where these surgical centres (Independent Sector Treatment Centres or ISTCs) would be built based on local patient waiting times – not length of stay or clinical quality – to construct treatment and control groups that are comparable with respect to key outcome variables of interest. Using a difference-in-difference estimation strategy, we find that the government-facilitated entry of surgical centres led to shorter pre surgery length of stay at nearby public hospitals. However, these new entrants took on healthier patients and left incumbent hospitals treating patients who were sicker. This paper highlights a potential trade-off that policymakers face when they promote competition from private, for-profit firms in markets for the provision of public services.

This paper examines the link between legislative politics, hospital behavior, and health care spending. When trying to pass sweeping legislation, congressional leaders can attract votes by adding targeted provisions that steer money toward the districts of reluctant legislators. This targeted spending provides tangible local benefits that legislators can highlight when fundraising or running for reelection. We study a provision - Section 508 – that was added to the 2003 Medicare Modernization Act (MMA). Section 508 created a pathway for hospitals to apply to get their Medicare payment rates increased. We find that hospitals represented by members of the House of Representatives who voted ‘Yea’ on the MMA were significantly more likely to receive a 508 waiver than hospitals represented by members who voted ‘Nay.’ Following the payment increase generated by the 508 program, recipient hospitals treated more patients, increased payroll, hired nurses, added new technology, raised CEO pay, and ultimately increased their spending by over $100 million annually. Section 508 recipient hospitals formed the Section 508 Hospital Coalition, which spent millions of dollars lobbying Congress to extend the program. After the vote on the MMA and before the vote to reauthorize the 508 program, members of Congress with a 508 hospital in their district received a 22% increase in total campaign contributions and a 65% increase in contributions from individuals working in the health care industry in the members’ home states. Our work demonstrates a pathway through which the link between politics and Medicare policy can dramatically affect US health spending.