Table 3.

Risk of bias assessment for the nonrandomized trials using the Cochrane ROBINS-I tool

Study	Bias due to confounding	Bias due to selection of participants	Bias in classification of interventions	Bias due to deviations from intended interventions	Bias due to missing data	Bias in measurement of outcomes	Bias in selection of the reported result	Overall
Smedley (1988) [24]
Pryor (1991) [25]
El-Nahas (2006) [26]
Gadzhiev (2020) [27]

The symbol indicates a low risk of bias, indicates a moderate risk of bias, and indicates a serious risk of bias.