1. Division of Rheumatology, Department of Internal Medicine, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, Seoul, Korea.
2. Division of Rheumatology, Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea.
3. Division of Rheumatology, Department of Internal Medicine, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
4. Division of Rheumatology, Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, Korea.
5. Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.