1. Center for Health Services Research, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA.
2. The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, Maryland, USA.
3. Center for Surgery and Public Health, Brigham and Women's Hospital, Boston, MA Massachusetts, USA.
4. Department of Orthopedic Surgery, Brigham and Women's Hospital, Boston, MA Massachusetts, USA.
5. Department of Health Policy and Management, Harvard Medical School, Boston, Massachusetts, USA.