Department of Obstetrics and Gynecology 2, Kawasaki Medical School, Okayama, Japan. Biostatistics Section, Department of Data Science, Center for Clinical Sciences, National Center for Global Health and Medicine, 1-21-1, Toyama, Shinjyuku-Ku, Tokyo, 162-8655, Japan. yuemura@hosp.ncgm.go.jp. Department of Nuclear Medicine, Kawasaki Medical School, Okayama, Japan. Department of Clinical Biostatistics, Graduate School of Medicine, Kyoto University, Kyoto, Japan. Soen Orthopaedics, Osteoporosis and Rheumatology Clinic, Hyogo, Japan. Bone and Joint Surgery, Seirei Hamamatu General Hospital, Shizuoka, Japan. School of Health Science, Tottori University Faculty of Medicine, Tottori, Japan. Kawasaki Medical School, Okayama, Japan. Touto Sangenjaya Rehabilitation Hospital, Tokyo, Japan. Japan Osteoporosis Foundation, Tokyo, Japan. Department of Internal Medicine, Research Institute and Practice for Involutional Diseases, Nagano, Japan.