Text and Data Mining valid from 2019-10-12
Received: 11 April 2019
Revised: 9 August 2019
Accepted: 4 September 2019
First Online: 12 October 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee of St. Johannes Hospital in Dortmund, Germany, and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: Informed consent was freely given and obtained from all participants in this study.