Risk of bias assessment
The risk of bias for the included studies was assessed by two
independent reviewers using the Cochrane Collaboration’s tool,16 and disagreements were resolved by consensus or a
third reviewer.17 Seven domains were considered in the
evaluation process: sequence
generation, allocation concealment, blinding, incomplete outcome data,
selective outcome reporting, and other potential sources of bias.
Studies were judged to be “low-risk bias” if all items were “low
risk” when one item was unclear risk bias, studies were rated as
“unclear risk of bias”. When one item was high risk, studies were
rated as “high-risk bias”. 18