Received: 12 January 2018
Accepted: 28 May 2018
First Online: 31 May 2018
Compliance with ethical standards
: 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 and did not require informed consent. Therefore, the Local Ethics Committee of the Medical Faculty of the University of Leipzig approved the study and waived informed consent.
: Manuel F. Struck, Sebastian Ewens, Johannes K. M. Fakler, Gunther Hempel, André Beilicke, Michael Bernhard, Patrick Stumpp, Christoph Josten, Sebastian N. Stehr, Hermann Wrigge, and Sebastian Krämer declare that they have no conflict of interest.
Free to read: This content has been made available to all.