[1] Natl Univ Singapore, Yong Loo Lin Sch Med, 10 Med Dr, Singapore 117597, Singapore
[2] Natl Univ Hlth Syst, Dept Med, Div Endocrinol, 1E Kent Ridge Rd, Singapore 119228, Singapore
[3] Natl Univ Hlth Syst, Dept Med, Div Neurol, 1E Kent Ridge Rd, Singapore 119228, Singapore
[4] Natl Univ Heart Ctr Singapore, Dept Cardiol, 1E Kent Ridge Rd, Singapore 119228, Singapore
[5] Natl Univ Hlth Syst, Dept Med, 1E Kent Ridge Rd, Singapore 119228, Singapore
[6] Univ Cambridge, Addenbrookes Hosp, Sch Clin Med, Hills Rd, Cambridge CB2 0SP, England