[1] Indiana Univ, Sch Med, Richard L Roudebush Vet Adm Med Ctr, Regenstrief Inst Hlth Care, Bloomington, IN 47401 USA
[2] Harvard Univ, Sch Med, Cambridge, MA 02138 USA
[3] RAND Corp, Santa Monica, CA 90406 USA
[4] Univ Calif Los Angeles, Sch Med, Los Angeles, CA USA
[5] Duke Univ, Med Ctr, Durham VAMC, Durham, NC USA
[6] Univ Kentucky, Sch Med, Lexington, KY 40536 USA
[7] Univ Calif Davis, Davis, CA 95616 USA
[8] Johns Hopkins Univ, Baltimore, MD 21218 USA
[9] Univ Aberdeen, Aberdeen AB9 1FX, Scotland