Funding for this research was provided by:
Bundesministerium für Bildung und Forschung (01ER1301A/B/C, 01ER1511D)
Received: 11 June 2019
Accepted: 23 July 2019
First Online: 31 July 2019
Ethics approval and consent to participate
: 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 study was approved by the Ethics committee of the local chamber of physicians in Bremen (Bremen Medical Association, reference number RE/HR-388). Written informed consent was obtained from all individual participants included in the study.
: Not applicable.
: The authors declare that they have no competing interests.