1. Kaiser Permanente, Division of Research, Oakland, California
2. University of Michigan Medical School, Ann Arbor, Michigan
3. University of Cincinnati College of Medicine, Cincinnati, Ohio
4. Kaiser Permanente, Division of Research, Oakland, California; Kaiser Permanente San Rafael Medical Center, Department of Emergency Medicine, San Rafael, California
5. Kaiser Permanente, Division of Research, Oakland, California; Kaiser Permanente Sacramento Medical Center, Department of Emergency Medicine, Sacramento, California