1. Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore
2. Department of Hospital Epidemiology, Veterans Affairs Maryland Health Care System, Baltimore, Maryland
3. Department of Medicine, School of Medicine, University of California, San Francisco
4. San Francisco Veterans Affairs Medical Center, San Francisco, California
5. Department of Pediatrics, University of Utah School of Medicine, Salt Lake City
6. Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
7. Center for Health Policy and Outcomes, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York
8. Department of Medicine, Weill Cornell Medical College, New York, New York