Funding for this research was provided by:
Bundesministerium für Bildung und Forschung (01EH1201B)
Received: 9 November 2018
Accepted: 20 May 2019
First Online: 11 June 2019
Ethics approval and consent to participate
: The researchers have obtained ethical approval for this study from the Ethics Committee of Hannover Medical School. As data was collected via a postal survey, participants agreed to participate in the study by sending the completed questionnaire back. There was no additional consent to participate.
: Not applicable.
: The authors declare that they have no competing interests.