Study concept and design: Leshem, Tate, Curns, Lopman, Parashar.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Leshem.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Leshem, Tate, Curns, Lopman, Parashar.
Obtained funding: Parashar.
Administrative, technical, or material support: Steiner, Curns.
Study supervision: Lopman, Parashar.
Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.
Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the US Centers for Disease Control and Prevention, the Agency for Healthcare Research and Quality, or the US Department of Health and Human Services.
Additional Contributions: We thank the partner states that voluntarily contributed their data to the Healthcare Cost and Utilization Project (http://www.hcup-us.ahrq.gov/partners.jsp).
Correction: This article was corrected on June 11, 2015, to fix the date range in the Figure title.