Funding for this research was provided by:
Damp Stiftung (Grant No. 2014-04)
Received: 1 August 2019
Accepted: 27 January 2020
First Online: 4 February 2020
Ethics approval and consent to participate
: The ethics committee of the General Medical Council of Hamburg approved the study protocol (reference number 4981). Written informed consent was obtained from all study participants.
: Not applicable.
: The authors declare that they have no competing interests.