1. Department of Family Medicine, University of North Carolina at Chapel Hill , Chapel Hill, NC , USA
2. Clinical Endoscopy Division, Boston Scientific Corporation , Marlborough, MA , USA
3. Department of Health Behavior, Gillings School of Global Public Health, University of North Carolina at Chapel Hill , Chapel Hill, NC , USA
4. Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill , Chapel Hill, NC , USA