Author Contributions: Dr Fowler 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: Van Spall, Fowler.
Acquisition of data: Van Spall, Toren, Fowler.
Analysis and interpretation of data: Van Spall, Kiss, Fowler.
Drafting of the manuscript: Van Spall, Kiss, Fowler.
Critical revision of the manuscript for important intellectual content: Van Spall, Fowler.
Statistical analysis: Kiss, Fowler.
Obtained funding: Fowler.
Administrative, technical, or material support: Fowler.
Study supervision: Fowler.
Financial Disclosures: None reported.
Funding/Support: Dr Fowler is a Career Scientist of the Ontario Ministry of Health and Long-term Care.
Role of the Sponsor: The sponsor had no role in the design; conduct of the study; collection, analysis, and interpretation of the data; or the preparation, review, or approval of the manuscript.
Acknowledgment: We thank the following people for their thoughtful review and suggestions on the methods and presentation of this work, none of whom were compensated: Steven Shumak, MD, Don Redelmeier, MD, MS, Neill Adhikari, MD, MSc, Damon Scales, MD, Ruxandra Pinto, PhD, Art Slutsky, MD, William Sibbald, MD, MPH (University of Toronto, Toronto, Ontario); Deborah Cook, MD, MSc (McMaster University, Hamilton, Ontario); Eva Shimaoka, MD (Toronto, Ontario); Daren Heyland, MD, MSc (Queen's University, Kingston, Ontario); and Gordon Rubenfeld, MD, MSc (University of Washington, Seattle). We dedicate this article to the memory of Aubrey Ignatius Van Spall.