Published Online: October 1, 2009 (doi:10.1001/jama.2009.1466).
Author Contributions: Dr Loeb had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Loeb, Webby, Smieja, Earn, Walter.
Acquisition of data: Loeb, Dafoe, Mahony, John, Sarabia, Glavin, Chong, Webb.
Analysis and interpretation of data: Loeb, Smieja, Chong, Walter.
Drafting of the manuscript: Loeb, Dafoe.
Critical revision of the manuscript for important intellectual content: Loeb, Mahony, John, Sarabia, Glavin, Webby, Smieja, Earn, Chong, Webb, Walter.
Statistical analysis: Loeb, Walter.
Obtained funding: Loeb, Walter.
Administrative, technical, or material support: Dafoe, John, Sarabia, Smieja, Earn, Chong, Webb.
Study supervision: Loeb, Mahony, Webby.
Financial Disclosures: None reported.
Funding/Support: This study was supported by the Public Health Agency of Canada.
Role of the Sponsor: The funding organization had no role in the design and conduct of the study; in the collection, analysis, and interpretation of the data; or in the preparation, review, or approval of the manuscript.