[1] Vanderbilt Univ, Sch Med Med Gastroenterol, Nashville, TN 37212 USA
[2] VA Tennessee Valley Hlth Care Syst, Nashville, TN 37212 USA
[3] Case Western Reserve Univ, Med Gastroenterol, Cleveland, OH 44106 USA
[4] VA Northeast Ohio Hlth Syst, Cleveland, OH USA
[5] McMaster Univ, Dept Hlth Res Methods Evidence & Impact, Hamilton, ON, Canada
[6] Univ Colorado, Anschutz Med Campus, Aurora, CO USA