1. Truven Health Analytics, 100 Phoenix Dr Ann Arbor, Ann Arbor, MI, 48108, United States of America
2. Truven Health Analytics, Bethesda, MD, United States of America
3. Agency for Healthcare Research and Quality, Center for Quality Improvement and Patient Safety, Rockville, MD, United States of America
4. National Center for Health Statistics, Office of Analysis and Epidemiology, Hyattsville, MD, United States of America