Funding for this research was provided by:
Hong Kong Council on Smoking and Health (NA)
Received: 1 April 2019
Accepted: 26 June 2019
First Online: 4 July 2019
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board of the University of Hong Kong/Hospital Authority Hong Kong West Cluster (IRB reference number: UW 17–084). All trial participants provided an informed and verbal consent.
: Not applicable.
: The funder was not involved in the collection, analysis and interpretation of the data, but two authors from the funder approved the submission of the manuscript.