[1] Univ Penn, Perelman Sch Med, Dept Med, Philadelphia, PA 19104 USA
[2] Univ Penn, Perelman Sch Med, Dept Biostat & Epidemiol, Philadelphia, PA 19104 USA
[3] Univ Penn, Perelman Sch Med, Ctr Clin Epidemiol & Biostat, Philadelphia, PA 19104 USA
[4] Philadelphia VA Med Ctr, Med Serv, Philadelphia, PA USA
[5] VA Connecticut Healthcare Syst, West Haven, CT USA
[6] Yale Univ, Sch Med, New Haven, CT USA
[7] VA Greater Los Angeles Healthcare Syst, Los Angeles, CA USA
[8] Univ Calif Los Angeles, David Geffen Sch Med, Los Angeles, CA 90024 USA
[9] McGill Univ, Ctr Hlth, Chron Viral Illness Serv, Montreal, PQ, Canada
[10] Atlanta VA Med Ctr, Atlanta, GA USA
[11] Emory Univ, Sch Med, Atlanta, GA 30322 USA
[12] Baylor Coll Med, Infect Dis Sect, Michael E DeBakey VA Med Ctr, Houston, TX 77030 USA
[13] Baylor Coll Med, Dept Med, Houston, TX 77030 USA
[14] VA Pittsburgh Healthcare Syst, Pittsburgh, PA 15240 USA
[15] Hamad Healthcare Qual Inst, Doha, Qatar
[16] Hamad Med Corp, Doha, Qatar
[17] George Washington Univ, Med Ctr, Washington DC VA Med Ctr, Washington, DC 20037 USA
[18] James J Peters VA Med Ctr, New York, NY USA
[19] Mt Sinai Sch Med, New York, NY USA
[20] Yale Univ, Sch Publ Hlth, New Haven, CT USA