Schiek, Susanne
Hildebrandt, Katja
Zube, Olaf
Bertsche, Thilo
Article History
Received: 18 January 2018
Accepted: 3 January 2019
First Online: 13 February 2019
Compliance with ethical standards
:
: The authors declare that they have no conflict 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. For this type of study (retrospective case-control study), formal consent is not required.