Fig. 4

The summary of the risk of bias assessed in the included studies. In this context, red color denotes a high risk, while light blue color signifies a low risk. X1 = was the sample representative of the target population; X2 = were study participants recruited in an appropriate manner; X3 = was the sample size adequate; X4 = were the research participants and the setting described in detail; X5 = was the data analysis performed with adequate coverage of the identified sample; X6 = were objective and standard criteria utilized to measure the condition; X7 = was the disease measured reliably; X8 = was there appropriate statistical/data analysis; and X9 = are all important confounding factors, subgroups, differences identified and accounted for. The figure was made using the ggplot2 and tidyr functions of RStudio.