Risk of Bias Assessment
Since only non-randomized studies are included in this review, one risk of bias assessment was performed. Two researchers worked together to complete the risk of bias assessment; after that, a third researcher compared and integrated the findings of this assessment. If there was any disagreement, the fourth investigator acted as tie-breaker. The Risk of Bias in Non-Randomized Studies of Interventions (ROBINS-I) tool was used to perform the risk assessment.
According to the traffic light plot of the risk of bias assessment (non-randomized studies), 81% had a low risk of bias (Table 1). 2 out of 6 studies were found to have a moderate risk of bias. None of the studies were found to have a critical risk of bias.
Table 1 . Traffic Light Plot of Risk of Bias Assessment (Non-Randomized Studies)