Abstract Many industries have become increasingly concentrated through mergers and acquisitions, which in health care may have important consequences for spending and outcomes. Using a rich panel of Medicare claims data for nearly one million dialysis patients, we advance the literature on the effects of mergers and acquisitions by studying the precise ways providers change their behavior following an acquisition. We base our empirical analysis on more than 1,200 acquisitions of independent dialysis facilities by large chains over a 12-year period and find that chains transfer several prominent strategies to the facilities they acquire. Most notably, acquired facilities converge to the behavior of their new parent companies by increasing patients’ doses of highly reimbursed drugs, replacing high-skill nurses with less-skilled technicians, and waitlisting fewer patients for kidney transplants. We then show that patients fare worse as a result of these changes: outcomes such as hospitalizations and mortality deteriorate, with our long panel allowing us to identify these effects from within-facility or within-patient variation around the acquisitions. Because overall Medicare spending increases at acquired facilities, mostly as a result of higher drug reimbursements, this decline in quality corresponds to a decline in value for payers. We conclude the article by considering the channels through which acquisitions produce such large changes in provider behavior and outcomes, finding that increased market power cannot explain the decline in quality. Rather, the adoption of the acquiring firm’s strategies and practices drives our main results, with greater economies of scale for drug purchasing responsible for more than half of the change in profits following an acquisition.

Medicare's prospective payment system for long-term acute-care hospitals (LTCHs) provides modest reimbursements at the beginning of a patient's stay before jumping discontinuously to a large lump-sum payment after a prespecified number of days. We show that LTCHs respond to the financial incentives of this system by disproportionately discharging patients after they cross the large-payment threshold. We find this occurs more often at for-profit facilities, facilities acquired by leading LTCH chains, and facilities colocated with other hospitals. Using a dynamic structural model, we evaluate counterfactual payment policies that would provide substantial savings for Medicare.

We study the effectiveness of pay-and-chase lawsuits and upfront regulations for combating health care fraud. Between 2003 and 2017, Medicare spent $7.7 billion on 37.5 million regularly scheduled ambulance rides for patients traveling to and from dialysis facilities even though many did not satisfy Medicare's criteria for receiving reimbursements. Using an identification strategy based on the staggered timing of regulations and lawsuits across the US, we find that adding a prior authorization requirement for ambulance reimbursements reduced spending much more than pursuing criminal and civil litigation did on their own. We find no evidence that prior authorization affected patients' health.