1. a Department of Family and Community Medicine , Wake Forest School of Medicine, Medical Center Blvd. , Winston-Salem , NC , USA
2. b Department of Epidemiology and Prevention, Division of Public Health Sciences , Wake Forest School of Medicine , Winston-Salem , NC , USA
3. c Department of Biostatistical Sciences , Division of Public Health Sciences, Wake Forest School of Medicine , Winston-Salem , NC , USA
4. d Department of Sociology , Wake Forest University , Winston-Salem , NC , USA