[1] Mayo Clin, Sect Colon & Rectal Surg, Jacksonville, FL 32224 USA
[2] Mayo Clin, Robert D & Patricia E Kern Ctr Sci Hlth Care Deli, Jacksonville, FL 32224 USA
[3] Mayo Clin, Dept Hlth Sci Res, Biostat Unit, Jacksonville, FL 32224 USA
[4] Mayo Clin, Div Colon & Rectal Surg, Rochester, MN USA