1. Department of Family Medicine, Seoul National University College of Medicine, Seoul, Korea.
2. Department of Family Medicine, Seoul Paik Hospital, Inje University College of Medicine, Seoul, Korea.
3. Department of Health Management, Inje Institute of Advanced Studies, Seoul, Korea.
4. Department of Laboratory Medicine, Seoul Paik Hospital, Inje University College of Medicine, Seoul, Korea.
5. Division of Rheumatology, Department of Medicine, Johns Hopkins University, Baltimore, USA.