1 Department of Clinical Research Design and Evaluation, SAIHST, Sungkyunkwan University, Seoul, South Korea.
2 Center for Clinical Epidemiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.
3 Welch Center for Epidemiology, Prevention, and Clinical Research, Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
4 Division of Endocrinology, Department of Internal Medicine, National Cancer Center, Goyang, South Korea.