Funding for this research was provided by:
SingHealth Foundation (SHF/FG462P/2011, SHF/FG462P/2011, SHF/FG462P/2011)
Article History
Received: 16 November 2017
Accepted: 19 June 2018
First Online: 6 July 2018
Competing Interests
: The authors declare no competing interests.