Received: 12 March 2018
Accepted: 22 July 2018
First Online: 31 July 2018
Ethics approval and consent to participate
: Institutional review board approval with waiver of informed consent of individual patients was obtained for this retrospective non-interventional study (The University of Hong Kong/ Hospital Authority Hong Kong West IRB: UW 15–315).
: Not applicable.
: All authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.