Text and Data Mining valid from 2018-04-11
Received: 5 December 2017
Accepted: 12 March 2018
First Online: 11 April 2018
Ethics approval and consent to participate
: This observational study was performed in accordance with the Helsinki declaration, European and French ethical laws.
: 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.