Katherine V. Williams and Richard K. Zimmerman are with the Department of Family Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA. Mary G. Krauland and Mark S. Roberts are with the Department of Health Policy and Management and Public Health Dynamics Laboratory, School of Public Health, University of Pittsburgh. Lee H. Harrison is with the Center for Genomic Epidemiology, Division of Infectious Diseases, University of Pittsburgh School of Medicine. John V. Williams is with the Departmen