Funding for this research was provided by:
Najran University
Article History
Received: 4 June 2018
Revised: 6 September 2018
Accepted: 21 September 2018
First Online: 7 January 2019
Compliance with ethical standards
:
: The scientific guarantor of this publication is Amaka C. Offiah.
: 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.
: Fabrizio Messina is a part time PhD student at the School of Health and Related Research, University of Sheffield and a Medical Statistician at the Leeds Institute of Clinical Trials Research, University of Leeds.
: Written informed consent was not required for this systematic review and meta-analysis.
: Institutional Review Board approval was not required for this systematic review and meta-analysis.
: • systematic review• meta-analysis