Table 2: Quality assessment of included randomized controlled trials.

Included trialsRandom sequence generationAllocation concealmentBlinding of participants and personnelBlinding of outcome assessmentIncomplete outcome dataSelective reportingOther sources of biasRisk of bias

Wei et al. 2003 [25]UnclearUnclearUnclearUnclearYesNoUnclearHigh
Han et al. 2010 [26]Stratified samplingUnclearUnclearUnclearYesNoUnclearUnclear
Wang et al. 2011 [27]UnclearUnclearUnclearUnclearYesNoUnclearHigh
Tang 2009 [28]UnclearUnclearUnclearUnclearYesNoUnclearHigh
Chen et al. 2011 [29]UnclearUnclearUnclearUnclearYesNoUnclearHigh
Mao and Sha 2006 [30]Stratified samplingUnclearUnclearUnclearNoNoUnclearUnclear
Yi et al. 1990 [31]UnclearUnclearUnclearUnclearYesNoUnclearHigh
Chen 2011 [32]UnclearUnclearUnclearUnclearYesNoUnclearHigh
He et al. 2011 [33]UnclearUnclearUnclearUnclearYesNoUnclearHigh
Lo et al. 2012 [34]UnclearUnclearUnclearUnclearYesNoUnclearHigh
Wang 2007 [35]UnclearUnclearUnclearUnclearYesNoUnclearHigh
Luo 2006 [36]UnclearUnclearUnclearUnclearYesNoUnclearHigh
Wang et al. 2007 [37]UnclearUnclearUnclearUnclearYesNoUnclearHigh
Zhou 2007 [38]UnclearUnclearUnclearUnclearYesNoUnclearHigh
Chen and Lv 2006 [39]UnclearUnclearUnclearUnclearYesNoUnclearHigh
Song and Yu 2011 [40]UnclearUnclearUnclearUnclearYesNoUnclearHigh
Wang et al. 2011 [41]UnclearUnclearUnclearUnclearYesNoUnclearHigh
Lee 2004 [42]UnclearUnclearUnclearUnclearYesNoUnclearHigh