1. Center for Surgical Trials and Outcomes Research, Johns Hopkins University School of Medicine, Baltimore, Maryland.
2. Department of Neurology, Johns Hopkins Hospital, Baltimore, Maryland.
3. International Neurorehabilitation Institute, Lutherville, Maryland.
4. International Center for Spinal Cord Injury, Hugo W. Moser Research Institute at Kennedy Krieger Institute, Baltimore, Maryland.
5. Division of Acute Care Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.
6. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.