[1] Univ Washington, Div Gastroenterol, VA Puget Sound Hlth Care Syst, Seattle, WA 98195 USA
[2] White River Junct VA Med Ctr, White River Jct, VT USA
[3] VA Cooperat Studies Program Coordinating Ctr, West Haven, CT USA
[4] Univ Colorado, Sch Med, Denver, CO 80202 USA
[5] VA Cooperat Studies Program, Albuquerque, NM USA
[6] Fred Hutchinson Canc Res Ctr, 1124 Columbia St, Seattle, WA 98104 USA
[7] Roudebush VA Med Ctr, Indianapolis, IN USA
[8] Portland VA Hlth Care Syst, Portland, OR USA
[9] VA Cooperat Studies Program Epidemiol Ctr, Durham, NC USA
[10] Minneapolis VA Med Ctr, Minneapolis, MN USA