1. a John Snow, JSI Research and Training Institute , Boston , MA , USA
2. b Department of Global Health and Social Medicine , Harvard Medical School , Boston , MA , USA
3. c Department of Health Care Policy , Harvard Medical School , Boston , MA , USA
4. d Department of Veterans Affairs Bedford Healthcare System , Center for Health Quality Outcomes and Economic Research , Bedford , USA
5. e Health Resources and Service Administration, HIV/AIDS Bureau , Rockville , MD , USA
6. f Yale School of Public Health , Yale School of Medicine , New Haven , CT , USA