Received: 12 April 2018
Accepted: 20 June 2018
First Online: 20 July 2018
Ethics approval and consent to participate
: This study was conducted according to the Ethical Guidelines of our institution, and no consent to participate was needed (Ethics Committee 412, CHR Citadelle, Liege, Belgium (study registration number: B412201835729)).
: Not applicable
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.