Text and Data Mining valid from 2017-07-25
Received: 2 November 2016
Accepted: 20 July 2017
First Online: 25 July 2017
Compliance with ethical standards
: No funding was received for this study.
: The authors declare that they have no conflict of interest.
: All procedures of 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.