Funding for this research was provided by:
Bundesministerium für Bildung und Forschung (01GY1337)
Received: 29 July 2020
Accepted: 3 February 2021
First Online: 20 February 2021
Ethics approval and consent to participate
: All procedures during data collection followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2013. Informed consent was obtained from all participants for being included in the study. The study was approved by the Ethics Committee of Ulm University (ref. nr. 224/14) and all study centres. The study was registered at the 07/10/2014 before the start of data collection (04/11/2014) at the German clinical trials register (Deutsches Register Klinischer Studien, DRKS, nr: DRKS00006806, ExternalRef removed).
: Not applicable.
: All authors declare that they have no conflict of interests.