Received: 12 March 2020
Revised: 10 June 2020
Accepted: 13 June 2020
First Online: 24 June 2020
Compliance with ethical standards
: All authors declare that they have no known conflicts 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 with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: This retrospective study was approved by our institutional review board, and the requirement for informed consent was waived.