Document is current

Article History

Received: 2 February 2017

Accepted: 9 February 2018

First Online: 1 March 2018

Authors’ information

: Not applicable.

: As this work is an overview of existing systematic reviews and uses secondary anonymised data without access to individual identifiers, approval and consent to participate was not required.

: All authors have provided consent for publication.

: The authors declare that they have no competing interests.

: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.