Accepted for Publication: September 14, 2012.
Published Online: February 25, 2013. doi:10.1001/jamaneurol.2013.929
Author Contributions:Study concept and design: Gordon, Mehal, Holman, L. P. Rowland, A. S. Rowland, and Cheek. Acquisition of data: Holman and Cheek. Analysis and interpretation of data: Gordon, Mehal, Holman, L. P. Rowland, A. S. Rowland, and Cheek. Drafting of the manuscript: Gordon, Mehal, Holman, A. S. Rowland, and Cheek. Critical revision of the manuscript for important intellectual content: Gordon, Mehal, Holman, L. P. Rowland, A. S. Rowland, and Cheek. Statistical analysis: Mehal, Holman, and A. S. Rowland. Study supervision: Gordon and Cheek.
Conflict of Interest Disclosures: None reported.
Disclaimer: The findings and conclusions in this article are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention or the IHS.
Additional Contributions: We thank Donald H. Reece, BS, and Barbara Strzelczyk, BS (both from IHS), for technical assistance; the staff at the health care facilities and the IHS National Patient Information Reporting System for participating; and Lawrence Schoenberger, MD, MPH, for his review of the paper and insights.