Article History
Received: 11 November 2019
Accepted: 10 December 2019
First Online: 21 December 2019
Compliance with ethical standards
:
: Francis Chan has been paid lecture fees by Pfizer Upjohn Korea Ltd. and AstraZeneca Sdn. Bhd., and he received education grant from Pfizer and Olympus. The other authors have nothing to declare.