Received: 17 March 2019
Accepted: 26 June 2019
First Online: 6 July 2019
Ethics approval and consent to participate
: This study was approved by the Ethics Committee of Zhejiang Provincial People’s Hospital, China (No. 2019KY001). A certificate of approval has been provided. The requirement of informed consent was exempted due to the retrospective nature of the study.
: Not applicable.
: The authors declare that they have no competing interests.