Reviewing procedure and study selection

Two investigators (LSN–AG) performed the review independently. The 1st step consisted of reviewing the titles and abstracts of all the references retrieved by the database searches (LSN–AG) and identifying the studies that met the inclusion criteria. Next, we selected all articles that were deemed potentially eligible by at least one of the reviewers. In the 2nd step, the reviewed the full texts, and a decision on inclusion or exclusion was made according to the predefined selection criteria (LSN–AG). A 3rd reviewer (MSR) solved any disagreement in any step. All studies that did not fulfil the predefined criteria were excluded, and their bibliographic details were listed with the specific reason for exclusion.