Received: 13 October 2019
Accepted: 24 December 2019
First Online: 7 January 2020
Ethics approval and consent to participate
: This study was approved by the Ethical Review Board of China Medical University Hospital (CMUH102-REC3-016). Informed consent of the study participants was not required because the dataset used in this study consists of de-identified secondary data released for research purposes.
: Not applicable.
: The authors declare that they have no competing interests.