Text and Data Mining valid from 2018-05-04
Received: 19 February 2018
Accepted: 27 April 2018
First Online: 4 May 2018
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 and national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standard.
: Informed consent was obtained from all individual participants included in the study.