Table 3. Risk of bias assessment of selected studies.

	Pre - Intervention		At intervention		Post - Intervention
	Bias due to confounding	Bias in selection of participants into the study	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
Suteerapongpun. et al., 2018	Low	Low	low	Low	low	moderate	low	moderate
Wang et al., 2017	Low	Low	moderate	Low	moderate	low	low	moderate
Jayakumar et al., 2012	low	Moderate	moderate	Low	low	low	low	moderate
Gracco et al., 2008	Low	Low	low	Low	low	moderate	low	moderate

ROBINS-I, Risk of Bias in Non-randomized Studies of Interventions.