Funding for this research was provided by:
University of Hong Kong
Received: 30 December 2018
Accepted: 19 June 2019
First Online: 9 July 2019
Ethics approval and consent to participate
: The Institutional Review Board of the University of Hong Kong/Hospital Authority Hong Kong West Cluster (UW09–435) approved this study. After reviewing a study information sheet, all participants provided written consent to participate in the study.
: Not applicable.
: The authors declare that they have no competing interests.