1. Harold Simmons Center for Kidney Disease Research and Epidemiology, University of California Irvine, School of Medicine, Orange, CA, USA
2. Department of Internal Medicine, Korea University School of Medicine, Seoul, Korea
3. Department of Internal Medicine, National Health Insurance Service Medical Center, Ilsan Hospital, Goyangshi, Gyeonggi–do, Korea
4. Department of Internal Medicine, Soon Chun Hyang University Hospital, Gumi, Korea
5. Nephrology Section, Memphis Veterans Affairs Medical Center, Memphis, TN, USA
6. Division of Nephrology, Department of Medicine, University of Tennessee Health Science Center, Memphis, TN, USA
7. Department of Medicine, Tibor Rubin Veteran Affairs Medical Center, Long Beach, CA, USA