Funding for this research was provided by:
Text and Data Mining valid from 2018-04-02
Received: 16 October 2017
Accepted: 22 March 2018
First Online: 2 April 2018
Ethics approval and consent to participate
: The Ethics Committee of Charité Universitätsmedizin Berlin reviewed the study protocol and approved the study (EA1/031/14; 20.02.2014). All participants gave written informed consent.
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.