Received: 26 May 2019
Accepted: 3 September 2019
First Online: 14 September 2019
Ethical approval and consent to participate
: The study was approved by the Ethics Committee of the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Germany (no. 28_13 B). All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki declaration and its later amendments.According to the Ethics Committee of the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Germany (no. 28_13 B), informed consent was not required from all individual participants included in the study, because the analyzed retrospective data were anonymized and did not contain any identifying information.
: The authors declare that they have no competing interests.