Owning the Agent: Hospital Influence on Physician Behaviors

The organizational structure of U.S. health care has changed dramatically in recent years, with nearly half of physicians now employed by hospitals. This trend toward increasing vertical alignment between physicians and hospitals may alter physician behavior relative to physicians remaining in independent or group practices. We examine the effects of such vertical alignment using an instrumental variable strategy and a clinical context facilitating well-defined episodes of care. We find relatively modest positive effects (point estimates of 7% or lower) on total Medicare payments per episode, characterized by an increase in billable activity among other integrated physicians alongside a large decrease in activity among non-integrated providers. Acquiring hospitals ultimately capture more revenue following a physician practice acquisition; yet, the smaller overall bundle of care generates no net savings to Medicare due to location-based payment rules favorable to hospitals. Institutional subscribers to the NBER working paper series, and residents of developing countries may download this paper without additional charge at www.nber.org.