Division of Rheumatology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan. First Department of Internal Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan. Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Aichi, Japan. Institute of Rheumatology, Tokyo Women's Medical University, Tokyo, Japan. Division of Hematology/Oncology, Indiana University School of Medicine, Indianapolis, Indiana, USA. Daiichi-Sankyo Co., Ltd., Tokyo, Japan. Departments of Radiology, Medicine and Orthopaedic Surgery, University of California, San Francisco, California, USA. Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands.