Text and Data Mining valid from 2019-08-14
Received: 5 June 2019
Accepted: 7 August 2019
First Online: 14 August 2019
Compliance with ethical standards
: There are no conflicts of interest.
: This study did not involve animals.
: 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 was a retrospective study; informed consent was not sought.