Author Contributions: All authors had full access to all of the data (including statistical reports and tables) in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Marra, Beattie, Graf, and Liu-Ambrose. Acquisition of data: Nagamatsu and Liu-Ambrose. Analysis and interpretation of data: Marra, Beattie, Robertson, Najafzadeh, Nagamatsu, and Liu-Ambrose. Drafting of the manuscript: Liu-Ambrose. Critical revision of the manuscript for important intellectual content: Marra, Beattie, Robertson, Najafzadeh, Graf, Nagamatsu, and Liu-Ambrose. Statistical analysis: Marra, Najafzadeh, and Liu-Ambrose. Obtained funding: Beattie, Graf, and Liu-Ambrose. Administrative, technical, and material support: Nagamatsu and Liu-Ambrose. Study supervision: Marra, Robertson, and Liu-Ambrose.