Physician Group Influences on Treatment Intensity and Health: Evidence from Physician Switchers

Treatment intensity varies remarkably across physicians, and physicians are increasingly working in groups. This paper tests whether group affiliation impacts physicians’ treatment intensity and patient health. Using Medicare inpatient claims data, we focus on internists who switch groups within the same hospital. Event studies show that internists who join more-intensive groups immediately increase their own intensity, with an elasticity of 0.27. This change is reflected in higher Medicare spending due to higher-priced services. We do not detect a change in health outcomes, suggesting that treatment intensity induced by group affiliation may not be productive.(JEL H51, I11, I13, I18, J44)