1 From the Center for Evidence Synthesis in Health and Departments of Health Services, Policy & Practice and Epidemiology, School of Public Health, Brown University, Providence, RI.
2 Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA.
3 Department of Biostatistics, Harvard School of Public Health, Boston, MA.
4 Harvard-MIT Division of Health Sciences and Technology, Boston, MA.