1. Department of Neurosurgery and University of Maryland School of Medicine, Baltimore, Maryland, USA.
2. R. Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, Maryland, USA.
3. School of Nursing and Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Ontario, Canada.
4. Walter Reed National Military Medical Center, Bethesda, Maryland, USA.