Author Contributions: Dr Healton had full access to all 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: Healton, Watson-Stryker, Vallone, Messeri, and Glantz. Acquisition of data: Watson-Stryker, Graham, and Stewart. Analysis and interpretation of data: Allen and Dobbins. Drafting of the manuscript: Healton, Watson-Stryker, and Allen. Critical revision of the manuscript for important intellectual content: Healton, Watson-Stryker, Allen, Messeri, Graham, Stewart, Dobbins, and Glantz. Statistical analysis: Messeri, Graham, and Glantz. Administrative, technical, and material support: Watson-Stryker, Allen, Stewart, and Dobbins. Study supervision: Allen and Vallone.