Text and Data Mining valid from 2019-01-17
Received: 19 November 2018
Accepted: 29 December 2018
First Online: 17 January 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: The research was carried out with the ethical standards of the institutional research and ethics committee (REC ref. 17/HRA/3148 ) and with the 1964 Helsinki declaration and its later amendments.
: Informed consent was not required for this study.