Text and Data Mining valid from 2019-01-16
Received: 7 July 2018
Accepted: 11 December 2018
First Online: 16 January 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: All procedures performed in this study were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: Informed consent was obtained from all individual participants included in the study. There were no financial, economic, or professional interests that influenced the design, execution, or presentation of this work.