Critical appraisal:Han JG, Wang ZJ, Wei GH, Gao ZG, Yang Y, Zhao BC 2012 2

Risk of bias assessment: Randomised Controlled Trial (Cochrane risk of bias tool)

Random sequence generation

Describe the method used to generate the allocation sequence in sufficient detail to allow an assessment of whether it should produce comparable groups.

Not described

What was the risk of bias from the random sequence generation?

Low

Allocation concealment

Describe the method used to conceal the allocation sequence in sufficient detail to determine whether intervention allocations could have been foreseen in advance of or during, enrolment.

Randomization was performed on the day before surgery through sealed opaque envelopes containing a surgical

method.

What was the risk of bias from the allocation concealment?

Low

Blinding

Describe all measures used, if any, to blind outcome assessors from knowledge of which intervention a participant received. Provide any information relating to whether the intended blinding was effective.

Not described

What was the risk of bias from the blinding of participants and personnel and outcome assessors?

Unclear

Incomplete outcome data

Describe the completeness of outcome data for each main outcome, including attrition and exlusions from the analysis. State whether attrition and exclusions were reported, the numbers in each intervention group (compared with total randomized participants), reasons for attrition/exclusions where reported, and any re-inclusions in analyses performed by the review authors.

All patient data included

What was the risk of bias from incomplete outcome data?

Low