Health spi llovers among hospi tal pati ents evidence from roommate assignments

This study examines health spillovers among hospital patients using a natural experiment of conditionally random hospital roommate assignments and electronic medical records data for a sample of 3,793 patients and their roommates. The study finds that positive health spillover effects may play an important role in reducing the amount of care the patient requires during hospitalization, shortening length of hospital stay, and lowering hospitalization cost, with little evidence of negative health effects for most patients. Mechanisms of roommate effects and implications for health-care delivery and policy are also considered.