1. Division of Colon and Rectal Surgery, Mayo Clinic, Jacksonville, FL, USA
2. Hospital Pharmacy Services, Mayo Clinic, Rochester, MN, USA
3. Department of Anesthesiology, Mayo Clinic, Rochester, MN, USA
4. Division of Colon and Rectal Surgery, Mayo Clinic, Rochester, MN, USA
5. Department of Biostatistics, University of Rochester, Rochester, MN, USA
6. Department of Statistics, Michigan State University, East Lansing, MI, USA