Table 2

Risk of bias among included studies

Cochrane Items
Selection biasPerformance biasDetection biasAttrition biasReporting bias
StudyRandom sequence generationAllocation concealmentBlinding of participants and personnelBlinding of outcome assessmentIncomplete outcome dataSelective reportingOtherNo. of high, %*
De Lima et al.86 (2019)LowLowLowLowLowLowLow0
Deppermann et al.115 (2014)HighLowLowLowUnsureLowLow14.29
Diefenbach et al.116 (2016)HighLowLowLowLowLowLow14.29
Dilkov et al.87 (2017)LowLowLowLowHighLowLow14.29
Herrmann et al.117 (2017)HighLowLowLowLowLowLow14.29
Huang et al.118 (2018)HighLowLowLowLowLowLow14.29
Mantovani et al.119 (2013)HighLowLowLowLowLowLow14.29
Movahed et al.120 (2018)HighLowHighHighLowLowLow42.86
Nasiri et al.121 (2020)HighHighLowLowLowHighLow42.86
Notzon et al.88 (2015)HighLowHighHighUnsureLowLow42.86
Prasko et al.122 (2007)HighLowLowLowLowLowLow14.29
  • * We calculated a percentage for each study, as the quotient of the number of “High” ratings and the total number of relevant items. The lower the percentage, the lower the overall risk of bias.