Funding for this research was provided by:
National Medical Research Council (NMRC/TCR/011-NUHS/2014, NMRC/CSA/0050/2013, NMRC/CG/013/2013)
Received: 15 December 2019
Accepted: 24 May 2020
First Online: 9 June 2020
Ethics approval and consent to participate
: Ethics approval were approved by the Domain Specific Review Board of the National Healthcare Group, Singapore (NHG-DSRB; DSRB study codes 2012/00932, 2013/00116, and 2014/01269). All study participants provided written informed consent.
: Not applicable.
: The authors report no conflict of interest.