1. Center for Vascular Emergencies Department of Emergency Medicine Massachusetts General Hospital Boston MA
2. Department of Clinical Epidemiology Leiden University Medical Center Leidenthe Netherlands
3. Department of Biostatistics Massachusetts General Hospital Boston MA
4. Department of Emergency Medicine State University of New York at Stony Brook Stony Brook NY
5. Department of Emergency Medicine University of Cincinnati Cincinnati OH
6. Division of Emergency Medicine Duke University Durham NC
7. Department of Emergency Medicine Thomas Jefferson University Philadelphia PA