Risk of bias
The quality of the evidence was classified as high, moderate, low, or very low, according to the risk of bias, clarity of comparisons, precision, and consistency of the analyzes. The randomized controlled clinical trials (RCTs) have given the highest preference, as it provides high scientific evidence. The quality of the evidence was reduced to moderate if one of the four criteria of quality of the evidence had not been met and lower if 2 or more were not met. Low quality of evidence was attributed to case reports, editorials, and short communications. The Cochrane instrument was to be adopted to assess the quality of the included studies [15].