Addressing the cost and quality challenges facing the U.S. health care system must begin with a focus on improving care for the sickest and most costly patients, say The Commonwealth Fund’s David Blumenthal, M.D., and Melinda Abrams in a new JAMA “Viewpoint” published online yesterday. The article is part of the National Academy of Medicine initiative Vital Directions in Health and Health Care, which aims to produce evidence-based health policy recommendations for the next president and administration.