[1] Harvard Univ, Sch Publ Hlth, Dept Epidemiol, Boston, MA 02115 USA
[2] Harvard Univ, Sch Publ Hlth, Dept Biostat, Boston, MA 02115 USA
[3] Univ Penn, Sch Med, Philadelphia Vet Affairs Med Ctr, Philadelphia, PA 19104 USA
[4] Univ Penn, Sch Med, Ctr Clin Epidemiol & Biostat, Philadelphia, PA 19104 USA
[5] VA Connecticut Healthcare Syst, West Haven, CT 06516 USA
[6] Yale Univ, Sch Med, New Haven, CT USA
[7] Boston Univ, Sch Publ Hlth, Dept Epidemiol, Boston, MA 02215 USA
[8] Boston Univ, Sch Med, Boston Med Ctr, Infect Dis Sect, Boston, MA 02215 USA
[9] Vet Affairs Greater Los Angeles Healthcare Syst, Los Angeles, CA USA
[10] Univ Calif Los Angeles, David Geffen Sch Med, Los Angeles, CA 90095 USA
[11] Atlanta Vet Affairs Med Ctr, Atlanta, GA USA
[12] Emory Univ, Sch Med, Atlanta, GA USA
[13] Michael E DeBakey VA Med Ctr, Houston, TX USA
[14] Baylor Coll Med, Houston, TX 77030 USA
[15] Univ Pittsburgh, Sch Med, Pittsburgh, PA 15260 USA
[16] Sheikh Khalifa Med City, Abu Dhabi, U Arab Emirates
[17] McGill Univ, Royal Victoria Hosp, Ctr Hlth, Montreal, PQ H3A 1A1, Canada