Text and Data Mining valid from 2018-07-05
Received: 12 December 2017
Accepted: 21 June 2018
First Online: 5 July 2018
Compliance with ethical standards
: The authors declare that there is no conflict of interest.
: This study was ethically approved by the National University Hospital (NUH) institutional review board (IRB) and the National Health Care Group (NHG) domain-specific review board (DSRB) under the reference number (2016/01003).
: For this type of study, formal consent is not required.