Network meta-analysis of randomized controlled trials on esophagectomies in esophageal cancer: The superiority of minimally invasive surgery

Table 2 The results of the risk of bias assessment by each domain

Ref.	Randomization process	Deviation from intended intervention	Missing outcome data	Measurement of the outcome	Selection of the reported results	Overall
Straatman et al[25]	Low risk	Low risk	Low risk	Low risk	Low risk	Low risk
van der Sluis et al[26]	Low risk	Low risk	Low risk	Low risk	Low risk	Low risk
Mariette et al[27]	Low risk	Low risk	Low risk	Low risk	Low risk	Low risk
Guo et al[28]	Unclear risk	Low risk	Low risk	Low risk	Unclear risk	Unclear risk
Ma et al[29]	Unclear risk	Unclear risk	Low risk	Low risk	Unclear risk	High risk
Jacobi et al[30]	Unclear risk	Unclear risk	Low risk	Low risk	Unclear risk	High risk
Goldminc et al[31]	Unclear risk	Unclear risk	Low risk	Low risk	Low risk	Unclear risk
Chu et al[32]	Unclear risk	Unclear risk	Low risk	Low risk	Unclear risk	High risk
Hulscher et al[33]	Low risk	Unclear risk	Low risk	Low risk	Unclear risk	Unclear risk
Yang et al[35]	Unclear risk	Unclear risk	Low risk	Low risk	Unclear risk	High risk
Paireder et al[34]	Low risk	Unclear risk	Low risk	Low risk	Unclear risk	Unclear risk

Risk of bias is indicated according to each domain of the Revised Cochrane risk-of-bias tool for randomized trials[23]. By the assessment of overall risk of bias, low risk of bias was given in the case of low risk of bias by every domain; if one or two domains were assessed as unclear risk of bias, unclear overall risk of bias was given, and if at least three domains were accompanied with unclear risk of bias, the overall risk of bias was assessed as high risk of bias.