Text and Data Mining valid from 2018-02-05
Received: 28 August 2017
Revised: 20 November 2017
Accepted: 28 November 2017
First Online: 5 February 2018
Compliance with ethical standards
: The scientific guarantor of this publication is Yousef Shahin.
: The authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article.
: One of the authors has significant statistical expertise.
: Institutional Review Board approval was not required because this study was a meta-analysis of published literature.
: Written informed consent was not required for this study because it was a systematic review and meta-analysis of published literature.
: • Systematic review and meta-analysis