Price effects of a hospital merger: heterogeneity across health insurers, hospital products, and hospital locations. Health Economics [PubMed] [RePEc] Published 1st July 2019
Most economics literature indicates that hospital mergers typically result in higher prices. But what does higher prices mean? Does it mean higher prices for all services? Higher prices for all health insurers?
Many economic models assume that hospitals charge a standard base rate and charges for individuals’ procedures are a fixed ratio of the base across all hospitals. This approach would make sense in a DRG-based system where prices are proportional to the product of a hospital’s base rate and the Medicare Severity DRG specific weight for a given hospitalization.
In practice, however, it is possible for prices to vary across procedures, across different negotiated contracts with insurers, and even across different locations within the same hospital system. For instance, the economic theory in this paper shows that the effect of a hospital merger increases prices most when an insurer’s bargaining power is high. Why? Because if the insurer had weak bargaining power, the hospital already would have high prices; the marginal impact is only felt when insurers had market power to begin with. Another interesting theoretical prediction is that if substitution between hospitals is stronger for service A than service B, prices will increase more for the former product, since the merger decreases the ability of consumers to substitute across hospitals due to decreased supply.
In their empirical applications, the authors use a comprehensive nationwide patient‐level data set from the Netherlands, on hospital admissions and prices. The study looks at three separate services: hip replacement, knee replacement, and cataract surgery. They use a difference-in-difference approach to measure the impact of a merger on prices for different services and across payers.
Although the authors did replicate earlier findings and showed that prices generally rise after a merger, the authors found significant heterogeneity. For instance, prices rose for hip replacements but not for knee replacements or cataracts. Prices rose for four health insurers but not for a fifth. In short, while previous findings about average prices still hold, in the real world, the price impact is much more heterogeneous than previous models would predict.