1. Division of Endocrinology and Metabolism, Department of Medicine, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea.
2. Division of Endocrinology and Metabolism, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
3. Department of Biostatistic, The Catholic University of Korea, Seoul, Korea.
4. Department of Statistics and Actuarial Science, Soongsil University, Seoul, Korea.
5. Division of Endocrinology and Metabolism, Department of Medicine, Kyung Hee University Hospital at Gangdong, Kyung Hee University School of Medicine, Seoul, Korea.
6. Department of Clinical Research Design and Evaluation, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, Korea.