1. Department of Internal Medicine, Chungbuk National University Hospital, Cheongju, Republic of Korea
2. Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea
3. Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
4. Arbor Research Collaborative for Health, Ann Arbor, MI, USA
5. Kidney Research Institute, Seoul National University Medical Research Center, Seoul, Republic of Korea