At leading medical centers, patients in intensive care units are often managed by doctors specially trained to provide that care—but a new study raises questions about the benefits of that treatment. Patients managed by critical care physicians were at greater risk of dying than patients managed by doctors who lacked that training, according to researchers who examined data from 123 U.S. intensive care units. The results were immediately challenged by the Society of Critical Care Medicine, and researchers acknowledged that more study is needed.