Laboratory Corporation of America(®) Holdings (LabCorp), Morrisville, NC, USA. Department of Medicine, Duke University Medical Center, Durham, NC, USA. Electronic address: john.guyton@duke.edu. Axio Research, Seattle, WA, USA. Department of Cardiology, Prevention and Imaging, University of Alabama, Birmingham, AL, USA. Mayo Clinic, Rochester, MN, USA. Department of Medicine, University of Washington, Seattle, WA, USA. Intermountain Medical Center, Murray, UT, USA; University of Utah, Salt Lake City, UT, USA. VA New England Healthcare System, Bedford, MA, USA; Massachusetts Veterans Epidemiology, Research, and Informatics Center (MAVERIC), and Boston University School of Medicine, Boston, MA, USA.