2.5. Risk of Bias Assessment

The three independent reviewers evaluated the risk of bias of the included studies using an adapted version of the Office of Health Assessment and Translation (OHAT) risk of bias tool for in vivo studies [26]. The tool is also applicable to access the potential risk of bias of in vitro studies. This tool of assessment includes the risk of bias in the following domains: (1) selection bias; (2) performance bias; (3) detection bias; (4) attrition bias; (5) reporting bias. Studies were judged as having a low risk of bias (+), high risk of bias (-), unclear risk of bias (?), and not applicable (NA). For the clinical studies, Cochrane Collaboration’s tool for assessing the risk of bias was used [27]. Any disagreement on the risk of bias assessment was resolved by further discussion between the reviewers.