1. Division of Public Health Sciences, Department of Biostatistical Sciences, Wake Forest University School of Medicine, Winston-Salem, NC.
2. College of Medicine, University of Arizona, Tucson, AZ.
3. Department of Family and Community Medicine, Wake Forest University School of Medicine, Winston-Salem, NC.
4. Division of Public Health Sciences, Department of Epidemiology and Prevention, Wake Forest University School of Medicine, Winston-Salem, NC.