The members contributing to the study include (in alphabetical order): Jin An, Kyung Hee University, Seoul, Korea; Surinder S. Birring, King’s College London, London, UK; Yoon-Seok Chang, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea; Sang-Heon Cho, Seoul National University Hospital, Seoul, Korea; Kian Fan Chung, Imperial College London, London, UK; Eun-Jung Jo, School of Medicine, Pusan National University, Busan, Korea; Noeul Kang, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea; Sung-Yoon Kang, Gachon University Gil Medical Center, Incheon, Korea; Byung-Keun Kim, Korea University College of Medicine, Seoul, Korea; Mi-Yeong Kim, Busan Paik Hospital, Inje University College of Medicine, Busan, Korea; Min-Hye Kim, College of Medicine, Ewha Womans University, Seoul, Korea; Sae-Hoon Kim, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea; Sang-Heon Kim, Hanyang University College of Medicine, Seoul, Korea; Sang-Hoon Kim, Eulji University College of Medicine, Seoul, Korea; Young-Chan Kim, Seoul National University Hospital, Seoul, Korea; Hyouk-Soo Kwon, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea; Byung-Jae Lee, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea; Ji-Ho Lee, Yonsei University Wonju College of Medicine, Wonju, Korea; Ji-Hyang Lee, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea; Hwa Young Lee, Seoul St Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea; Seung-Eun Lee, Pusan National University Yangsan Hospital, Yangsan, Korea; Ji-Yong Moon, Hanyang University College of Medicine, Seoul, Korea; Ji-Yoon Oh, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea; Han-Ki Park, Kyungpook National University Chilgok Hospital, School of Medicine, Kyungpook National University, Daegu, Korea; So-Young Park, Chung-Ang University College of Medicine, Seoul, Korea; Ji-Su Shim, College of Medicine, Ewha Womans University, Seoul, Korea; Woo-Jung Song, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea; Ha-Kyeong Won, Veterans Health Service Medical Center, Seoul, Korea; Youngsang Yoo, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung, Korea.