Received: 17 September 2019
Accepted: 11 March 2020
First Online: 19 March 2020
Ethics approval and consent to participate
: This study was approved by the institutional review board of Taichung Veterans General Hospital, Taichung, Taiwan (approval number: CE19214A). A certificate of approval has been provided. Due to the retrospective nature of the study, formal informed consent from the participants was not required.
: Not applicable.
: The authors declare that they have no competing interests.