1 Department of Medicine, Section of General Internal Medicine, Clinical Addiction Research and Education (CARE) Unit, School of Medicine/Boston Medical Center, Boston University, Boston, MA, USA; Department of Community Health Sciences, School of Public Health, Boston University, Boston, MA, USA. Electronic address: jsamet@bu.edu.
2 Department of Medicine, Section of General Internal Medicine, Schools of Medicine and Public Health, Yale University, New Haven, CT, USA; Department of Health Policy and Management and the Center for Interdisciplinary Research on AIDS, School of Public Health, Yale University, New Haven, CT, USA.