[1] VA Northern Calif Hlth Care Syst, 10535 Hosp Way, Mather, CA 95655 USA
[2] Calif Pacific Med Ctr, Res Inst, San Francisco Coordinating Ctr, San Francisco, CA USA
[3] Univ Alabama Birmingham, Heersink Sch Med, Div Prevent Med, MT 619,1720 2nd Ave S, Birmingham, AL 35294 USA
[4] Minneapolis VA Healthcare Syst, 1 Vet Dr, Minneapolis, MN 55417 USA
[5] Univ Minnesota, Dept Med, Minneapolis, MN USA
[6] Univ Alabama Birmingham, UAB Sch Publ Hlth, Dept Biostat, Birmingham, AL USA
[7] Univ Minnesota, Med & Epidemiol & Community Hlth, Minneapolis, MN USA
[8] Minneapolis VA Hlth Care Syst, One Vet Dr,Gen Internal Med 111-0, Minneapolis, MN 55417 USA
[9] Kaiser Permanente Ctr Hlth Res, 3800 North Interstate, Portland, OR 97227 USA
[10] Univ Pittsburgh, Sch Publ Hlth, Dept Epidemiol, A 510 Crabtree Hall,130 Desoto St, Pittsburgh, PA 15261 USA
[11] Harvard Med Sch, Brigham & Womens Hosp, 221 Longwood Ave, Boston, MA 02115 USA
[12] Univ Minnesota, Minneapolis, MN USA
[13] Univ Calif Davis Hlth, 451 Hlth Sci Dr,Suite 6515, Davis, CA 95616 USA