Text and Data Mining valid from 2018-04-02
Received: 10 December 2017
Accepted: 17 February 2018
First Online: 2 April 2018
Ethics approval and consent to participate
: The study design and its procedures have been presented to the local ethics committee who, according to the Danish law, did not consider the study for ethical approval, owing to the observational nature of the study.
: The authors declares that they have no competing interests.