Funding for this research was provided by:
Text and Data Mining valid from 2018-08-06
Received: 31 May 2018
Accepted: 21 July 2018
First Online: 6 August 2018
Compliance with ethical standards
: The authors declare they have no conflicts of interest.
: This study was approved by our institutional review board and has been performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments.
: Informed consent was obtained from all individual participants included in the study.