1. Division of General Internal Medicine, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
2. Nicotine Research Program, Mayo Clinic, Rochester, Minnesota, USA
3. Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota, USA
4. Complementary and Integrative Medicine, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
5. Division of Primary Care Internal Medicine, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA