Additional file 4: Summary of risk of bias in included studies Overall risk of bias data outcome (detection outcome (selection bias) concealment bias) bias) reporting of sequence bias Random Allocation Blinding Other bias) assessment bias) generation Selective (selection (attrition (reporting Incomplete Botha 2014 Low/ unclear Cai 2015 Low/ unclear Chatterjee Low 2014 Ghadiri 2015 High Hegde 2012 High Li 2005 High Ran 2015 Low/ unclear Sharifi 2012 High Sungur 2011 Low/ unclear Xiang 1994 Low/ unclear Zhang 1994 Low/ unclear
Additional file 4: Summary of risk of bias in included studies Random sequence generation (selection bias) Allocation concealment (selection bias) Blinding of outcome assessment (detection bias) Incomplete outcome data (attrition bias) Selective reporting (reporting bias) Other bias Overall risk of bias Botha 2014 Low/ unclear Cai 2015 Low/ unclear Chatterjee 2014 Low Ghadiri 2015 High Hegde 2012 High Li 2005 High Ran 2015 Low/ unclear Sharifi 2012 High Sungur 2011 Low/ unclear Xiang 1994 Low/ unclear Zhang 1994 Low/ unclear