1. Department of Public Health Sciences, Section on Epidemiology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1063; .
2. Section on Epidemiology, Department of Public Health Sciences, Wake Forest University School of Medicine.
3. Department of Family and Community Medicine at Wake Forest University School of Medicine.
4. Section on Biostatistics, Department of Public Health Sciences, at Wake Forest University School of Medicine.