Meta-analysis was performed with RevMan 5.3 software.



RevMan 5.3
We searched electronic databases such as CNKI, CBM, PubMed, Embase, and Cochrane Library up to January 2015. 
CNKI
We searched electronic databases such as CNKI, CBM, PubMed, Embase, and Cochrane Library up to January 2015. 
CBM
We searched electronic databases such as CNKI, CBM, PubMed, Embase, and Cochrane Library up to January 2015. 
PubMed
We searched electronic databases such as CNKI, CBM, PubMed, Embase, and Cochrane Library up to January 2015. 
Embase
We searched electronic databases such as CNKI, CBM, PubMed, Embase, and Cochrane Library up to January 2015. 
Cochrane Library