1 Department of Quantitative Methods, Harvard T. Chan School of Public Health, Boston, Massachusetts, USA.
2 School of Medicine , University of California San Francisco, San Francisco, California, USA.
3 Department of Medicine, Section of General Internal Medicine, Boston Medical Center, Boston, Massachusetts, USA.
4 Department of Health Law, Policy and Management, Boston University School of Public Health, Boston, Massachusetts, USA.
5 Clinical Addiction Research and Education Unit, Section of General Internal Medicine, Department of Medicine, Boston University School of Medicine, and Boston Medical Center, Boston, Massachusetts, USA.
6 Grayken Center for Addiction, Boston Medical Center, Boston, Massachusetts, USA; University of Massachusetts School of Medicine, Worcester, Massachusetts, USA.
7 Department of Biostatistics, Harvard School of Public Health, Boston, Massachusetts, USA.
8 Boston Health Care for the Homeless Program, Boston, Massachusetts, USA.
9 Division of Global Health Equity, Department of Internal Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA.