[1] Natl Univ Singapore, Yong Loo Lin Sch Med, 10 Med Dr, Singapore 117597, Singapore
[2] Natl Univ Singapore, Saw Swee Hock Sch Publ Hlth, Biostat & Modelling Domain, Singapore, Singapore
[3] Natl Univ Hlth Syst, Natl Univ Ctr Organ Transplantat, Singapore, Singapore
[4] Natl Univ Singapore Hosp, Dept Med, Div Gastroenterol & Hepatol, Tower Block Level 10,1E Kent Ridge Rd, Singapore 119228, Singapore
[5] Virginia Commonwealth Univ, Div Gastroenterol & Hepatol, Richmond, VA USA
[6] Queen Mary Hosp, Dept Med, Div Gastroenterol & Hepatol, Hong Kong, Peoples R China