Article History
Received: 26 October 2017
Accepted: 3 February 2018
First Online: 13 February 2018
Compliance with ethical standards
:
: The authors declare that they have no conflict of interest.
: The study protocol was approved by the local institutional research ethics committee, Institutional Review Board of the Hospital Authority Kowloon East Cluster (reference number KC/KE-17-0117/ER-4). The study firmly adhered to the tenets of the 1964 Helsinki Declaration and its later amendments. For this type of study, formal consent is not required.