[1] Columbia Univ, Med Ctr, 622 West 168th St,PH8-E Room 101, New York, NY 10025 USA
[2] Calif Pacific Med Ctr, Res Inst, San Francisco, CA USA
[3] Univ Calif San Francisco, Dept Epidemiol & Biostat, San Francisco, CA 94143 USA
[4] Univ Minnesota, Minneapolis, MN USA
[5] Minneapolis VAHCS, Minneapolis, MN USA
[6] Univ Calif Davis, Davis, CA 95616 USA
[7] Univ Calif San Diego, San Diego, CA 92103 USA
[8] Merck & Co Inc, N Wales, PA USA