Article History
Received: 16 August 2019
Accepted: 1 January 2020
First Online: 21 January 2020
Compliance with ethical standards
: This study was approved by the ethics review board of China Medical University (CMUH-104-REC2–115).
: Ying-Ying Wu, Chia-Ling Chang, Jen-Hung Wang, and Wei-Ting Wei declare that they have no conflict of interest.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
: This article does not describe any studies with human participants or animals performed by any of the authors.
: For this type of study, formal consent is not required.