1. From the Division of General Medicine and Clinical Epidemiology, Department of Medicine, University of North Carolina at Chapel Hill School of Medicine, and the Cecil G. Sheps Center for Health Services Research, University of North Carolina at Chapel Hill, Chapel Hill (S.A.B., C.W.C.); and the Division of General Internal Medicine, Department of Medicine, Boston University School of Medicine and Boston Medical Center, and Boston Health Care for the Homeless Program — both in Boston (A.C.).