Received: 7 December 2019
Accepted: 12 March 2020
First Online: 3 April 2020
Ethics approval and consent to participate
: This study involves human data, and institutional review board approval was obtained (Singhealth CIRB 2015/2134) before the start of this single-centre retrospective cohort study.
: Not applicable.
: The authors declare that they have no competing interests.