Risk of bias assessment

The Cochrane^®risk of bias tool (Cochrane collaboration, Oxford, UK) was used to check the risk of bias from the included studies. ²² This tool is composed of five domains, which altogether address the methodological aspects that can influence the results of a trial. Each of the five domains have specific questions that allow five possible answers (“yes”, “probably yes”, “no”, “probably no”, and “no information”). Based on this, each domain was classified into “low”, “unclear”, or “high” risk of bias, at the author’s discretion (GHO), who assessed all the studies. The main purpose of this process was to assess the rigor of the studies’ methodology and therefore, it was not used as an exclusion criterion.