[1] Baylor Coll Med, Dept Med, Div Gastroenterol, Houston, TX 77030 USA
[2] Baylor Coll Med, Micheal E DeBakey VAMC, Houston Ctr Qual Care & Utilizat Studies, Houston, TX 77030 USA
[3] Vanderbilt Univ, Div Gastroenterol, Vet Affairs Tennessee Valley Healthcare Syst, Dept Prevent Med, Nashville, TN USA
[4] Vanderbilt Univ, Dept Med, Nashville, TN USA