1. Center for Health Services Research, Uniformed Services University of the Health Sciences , Bethesda, MD 20814, USA
2. The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. , Bethesda, MD 20817, USA
3. Department of Global and Community Health, George Mason University , Fairfax, VA 22030, USA
4. Department of Orthopaedic Surgery, Brigham and Women’s Hospital, Harvard Medical School , Boston, MA 02115, USA
5. Department of Surgery, Uniformed Services University of the Health Sciences , Bethesda, MD 20814, USA
6. Center for Surgery and Public Health, Brigham and Women’s Hospital, Harvard Medical School , Boston, MA 02120, USA