Text and Data Mining valid from 2018-01-24
Received: 18 July 2017
Accepted: 14 January 2018
First Online: 24 January 2018
Compliance with ethical standards
: The protocol was developed according to the Cochrane Handbook for Systematic Reviews of Interventions (Higgins and Green CitationRef removed), was registered with PROSPERO [CRD42017052446] and followed the PRISMA guidelines (Moher et al. CitationRef removed).
: The authors declare that they have no conflict of interest.