Published on in Vol 5 , No 12 (2017) :December
Preprints (earlier versions) of this paper are
available at
https://preprints.jmir.org/preprint/8458, first published
.

1 Facultad de Enfermería, Fisioterapia y Podología, Universidad de Complutense de Madrid, Madrid, ES
2 Universidad Rey Juan Carlos, Alcorcon, ES
*all authors contributed equally