Table 2: Risk of bias of included RCTs*.

StudyRandom sequence generationAllocation concealment Patient blinding Assessor blindingReporting drop-out or withdrawalIntention-to-treat analysisSelective outcome reportingOther potential bias

Wang et al. 2010 [7]LowLowLowLowLowLowLowLow
Hsiao et al. 2003 [8]UnclearLowLowLowLowHighLowUnclear
Özsoy and Ernst 1999 [9]LowLowLowLowLowHighLowLow
Liu et al. 2005 [10]LowLowLowLowLowHighLowLow
Bishop et al. 2007 [11]LowLowLowLowLowLowLowLow
Tsao et al. 2005 [12]LowLowLowLowLowHighLowLow
Higgins et al. 2011 [24]UnclearLowLowLowLowLowLowUnclear
Burack et al. 1996 [13]LowHighHighHighLowLowLowUnclear
Sangkitporn et al. 2005 [14]LowLowLowLowLowLowLowLow
Shi and Peng 2003 [15]LowLowLowHighLowLowLowUnclear
Wang et al. 2006 [16]LowLowLowLowLowLowLowLow

Domains of quality assessment based on Cochrane tools for assessing risk of bias.
Two domains referring to “incomplete outcome data” in the Cochrane tools for assessing risk of bias.
Abbreviations: low: low risk of bias; high: high risk of bias; unclear: uncertain risk of bias.