Text and Data Mining valid from 2019-09-07
Received: 31 July 2019
Accepted: 29 August 2019
First Online: 7 September 2019
Compliance with ethical standards
: This study was not sponsored by any organization. The authors have no conflict of interests.
: 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. The data were gathered retrospectively, and without mentioning any details regarding the subjects.