Received: 2 February 2020
Accepted: 11 June 2020
First Online: 20 June 2020
Compliance with ethical standards
: All authors and co-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. The ethics committee of the general medical council for the city of Hamburg (Ärztekammer Hamburg; PV4764) approved the study.
: All subjects gave their written informed consent.