Funding for this research was provided by:
Text and Data Mining valid from 2019-04-08
Received: 4 February 2019
Accepted: 2 April 2019
First Online: 8 April 2019
Compliance with Ethical Standards
: The authors declare that they have no conflict of interest.
: For this type of study, formal institutional review board consent is not required. Informed consent was obtained from all individual participants included in the study.