Funding for this research was provided by:
Received: 6 November 2019
Accepted: 16 May 2022
First Online: 26 May 2022
: The study was approved by the local ethics committee (Ethics Committee University Duisburg-Essen, file number 14-6139-BO) and was conducted in accordance with the Helsinki Declaration of 1975, as revised in 2008.
: Not applicable.
: The authors declare no conflict of interest.