1. Wallace Trials Center, Greenwich Hospital, Greenwich, Connecticut;
2. Department of Neurosurgery, Lahey Clinic, Burlington, Massachusetts;
3. Department of Neurosurgery, University of Virginia, Charlottesville, Virginia;
4. Carolina Neurosurgery & Spine, Charlotte, North Carolina;
5. University of Medicine and Dentistry of New Jersey, Newark, New Jersey;
6. Institute for Clinical Research and Health Policy Studies, Tufts University Medical Center, Boston, Massachusetts;
7. Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania;
8. Department of Clinical Neurosciences, University of Calgary Spine Program, Calgary, Alberta, Canada;
9. Department of Neurological Surgery, University of California, San Francisco, California;
10. Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee;
11. Department of Neurosurgery, Columbia University, New York, New York;
12. Department of Neurosurgery, Yale University School of Medicine, New Haven, Connecticut;
13. Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland; and
14. Department of Neurological Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin