Author Contributions: Dr Katz 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: Sarnak, Katz, Fried, Siscovick, Seliger, Newman, and Shlipak. Acquisition of data: Katz, Siscovick, Tracy, Newman, and Shlipak. Analysis and interpretation of data: Sarnak, Katz, Fried, Siscovick, Kestenbaum, Seliger, Rifkin, Tracy, and Newman. Drafting of the manuscript: Sarnak and Katz. Critical revision of the manuscript for important intellectual content: Sarnak, Katz, Fried, Siscovick, Kestenbaum, Seliger, Rifkin, Tracy, Newman, and Shlipak. Statistical analysis: Katz, Siscovick, Kestenbaum, and Shlipak. Obtained funding: Sarnak, Siscovick, and Shlipak. Administrative, technical, and material support: Tracy and Newman.