Funding for this research was provided by:
Received: 13 July 2020
Accepted: 20 January 2021
First Online: 9 February 2021
Compliance with ethical standards
: All authors declare that they have no conflict of interest.
: The ethics committee of the Medical Faculty at the University of Heidelberg granted permission to conduct the study (project no S-481/2009). The study was performed according to the Declaration of Helsinki on biomedical research involving human subjects. All patients were informed about the study aims and protocol, and participants were enrolled after giving informed written consent.
: Informed consent was obtained from all individual participants included in the study.