2.5. Risk of Bias/Quality Assessment
Thanks to the abundance of non-randomized studies showing in the available literature, two independent reviewers (XXX and XXX) critically appraised all the eligible studies with Methodological Index for Nonrandomized Studies (MINORS) to assess the quality of included studies. A senior reviewer made the final decision on the assessment if a consensus was not achieved and supervised the entire process. The MINORS instrument contains 12 items: 4 for comparative studies and 8 for noncomparative studies. A score of 0 (not reported), 1 (reported but inadequate), or 2 (reported and adequate) was given for each item, resulting in an ideal maximum score of twenty-four for comparative studies and sixteen for noncomparative studies. For non-randomized studies, the methodologic quality was assessed as follows: 0 to 5, very low quality of evidence; 6 to 10, low quality; 11 to 15, fair quality; 16, good quality. The outcomes of the risk-of-bias and quality assessment provided the confidence level for the conclusions to be drawn from this review.