1. Baystate Medical Center, Springfield, MA, USA
2. Tufts University School of Medicine, Boston, MA, USA
3. Allies in Recovery, Northampton, MA, USA
4. Methodological Consultant, Amherst, MA, USA
5. School of Public Health, University of Illinois at Chicago, Chicago, IL, USA
6. Community Outreach Intervention Projects and Healthy Youths Program, University of Illinois at Chicago, Chicago, IL, USA
7. Yale AIDS Program, Section of Infectious Diseases, Yale School of Medicine, New Haven, CT, USA
8. Division of Infectious Diseases, The Miriam Hospital, Providence, RI, USA
9. Section of Infectious Diseases, Yale University, New Haven, CT, USA
10. Division of Epidemiology of Microbial Diseases, Yale University, New Haven, CT, USA
11. AIDS Care Group, Chester, PA, USA
12. New York City Department of Health and Mental Hygiene, East Elmhurst, NY, USA
13. School of Social Work, Temple University, Philadelphia, PA, USA