Article History
Received: 26 May 2018
Accepted: 4 October 2018
First Online: 26 October 2018
Compliance with ethical standards
:
: The authors declare no conflict of interest. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
: All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. There was no evaluation or vote of an Ethical Committee necessary because this study was designed as a meta-analysis.