Published Online: August 19, 2013. doi:10.1001/jamainternmed.2013.10013.
Study concept and design: All authors.
Acquisition of data: Guy, Berkowitz.
Analysis and interpretation of data: Guy, Berkowitz, Holman.
Drafting of the manuscript: Guy.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Guy, Berkowitz.
Administrative, technical, or material support: Guy, Watson, Holman, Richardson.
Study supervision: Guy, Richardson.
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.