Text and Data Mining valid from 2019-10-20
Received: 28 January 2019
Accepted: 3 September 2019
First Online: 20 October 2019
Ethics approval and consent to participate
: The study has been approved by the pertinent ethics committees and has been carried out in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. All persons gave their informed consent prior to their inclusion in the study.
: Not applicable.
: The authors declare they have no conflict of interest.