Funding for this research was provided by:
Text and Data Mining valid from 2019-07-08
Received: 17 April 2019
Accepted: 30 June 2019
First Online: 8 July 2019
Ethics approval and consent to participate
: The study was approved by the ethics board of the Catholic University Eichstätt-Ingolstadt in December 2016 (ethics approval number: 2016/23). All participants and their legal guardians gave their written informed consent to participate in the study.
: Not applicable.
: The authors declare that they have no competing interests.