[1] Univ Pittsburgh, Med Ctr, Pittsburgh, PA USA
[2] McMaster Univ, Dept Hlth Res Methods Evidence & Impact, Hamilton, ON, Canada
[3] Natl Inst Hlth Clin Ctr, Crit Care Med Dept, Bethesda, MD USA
[4] Loma Linda Univ Hlth, Loma Linda, CA USA
[5] Univ Pittsburgh, Sch Med, Pittsburgh, PA USA
[6] Natl Inst Hlth Lib, Bethesda, MD USA