1. Division of Rheumatology, Department of Internal Medicine, The Rheumatism Research Center, The Catholic University of Korea College of Medicine, Seoul 137-701, Korea.
2. Division of Rheumatology, Department of Internal Medicine, Hallym University Kang-Nam Sacred Heart Hospital, Seoul 150-950, Korea.
3. Department of Internal Medicine, Pusan National University College of Medicine, Busan 602-739, Korea.