1. Department of Internal Medicine, Division of Rheumatology, Hanyang University College of Medicine and the Hospital for Rheumatic Diseases, Seoul, Korea
2. Department of Internal Medicine, Division of Rheumatology, Hanyang University College of Medicine and the Hospital for Rheumatic Diseases, Seoul, Korea; Hospital for Rheumatic Diseases, Hanyang University Medical Center, Seoul 133-792, Korea
3. Department of Clinical Pathology, Hanyang University College of Medicine and the Hospital for Rheumatic Diseases, Seoul, Korea