Published on in Vol 6 , No 2 (2018) :February
Preprints (earlier versions) of this paper are
available at
https://preprints.jmir.org/preprint/8996, first published
.

1 University of Oulu, Oulu, Finland
2 Salumedia Tecnologias, Seville, Spain
3 Kliniken Valens, Valens, Switzerland
4 Universidad de Sevilla, Seville, Spain