2.6 Assessment of risk of bias in the included trials
The Cochrane risk of bias tool was used to assess the risk of bias in
the included studies. The tool contains six items addressing the
possible different types of bias within clinical trials which include
selection bias, performance bias, detection bias, attrition bias,
reporting bias and other bias (22). The first domain of selection bias
is divided into random sequence generation and allocation concealment
(22). RevMan Web 5.3 software application (Review Manager Web. The
Cochrane Collaboration, 2019) was used to plot the results of the risk
of bias assessment (23). The judgments were of a low, high or unclear
risk of bias for each study, regarding each domain.