[1] Baylor Coll Med, Dept Med, Sect Gastroenterol & Hepatol, Houston, TX 77030 USA
[2] Michael E DeBakey VA Med Ctr, Houston VA HSR&D Ctr Innovat Qual Effectiveness &, Houston, TX USA
[3] Baylor Coll Med, Dept Med, Sect Epidemiol & Populat Sci, Houston, TX 77030 USA
[4] Baylor Coll Med, Dan L Duncan Comprehens Canc Ctr, Houston, TX 77030 USA