1. Center for Quality Improvement and Patient Safety, Agency for Healthcare Research and Quality, 540 Gaither Road, Rockville, MD 20850, USA
2. ML Barrett, Inc, 13943 Boquita Drive, Del Mar, CA 92014, USA
3. Truven Health Analytics, Inc., 7700 Old Georgetown Road, Suite 650, Bethesda, MD 20814, USA
4. Truven Health Analytics and ML Barrett, Inc, 7700 Old Georgetown Road, Suite 650, Bethesda, MD 20814
5. Department of Neurology, The Johns Hopkins University School of Medicine, Meyer Building 8-154, 600 North Wolfe Street, Baltimore, MD 21287, USA