1 Cecil G. Sheps Center for Health Services Research and Department of Family Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC. Electronic address: Philip_Sloane@med.unc.edu.
2 Department of Health Services, Policy & Practice, School of Public Health, Brown University, and Center of Innovation, VA Medical Center, Providence, RI.
3 Department of Biostatistics, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC.