Table 2. Quality assessment: Risk of bias.

	Behnammoghadam et al., 2015 [45]	Dominguez et al., 2020 [46]	Gauhar & Wajid, 2016 [54]	Hase et al, 2018 [47]	Hogan, 2001 [48]	Kao et al., 2018 [55]	Moritz et al., 2018 [31]	Ostacoli et al., 2018 [56]	Passoni, 2018 [57]	Rahimi, 2018 [58]	Su, 2018 [59]
Bias arising from the randomisation process	-	+	?	+	?	?	+	+	?	?	?
Bias due to deviations from the intended interventions	-	?	?	?	-	?	?	?	?	?	?
Bias due to missing outcome data	-	+	?	-	-	?	+	?	+	+	+
Bias in the measurement of the outcome	?	+	?	?	?	?	?	?	?	?	?
Bias in the selection of the reported results	+	+	+	+	+	+	+	+	+	+	+
Therapist allegiance	-	+	-	-	?	-	NA	?	-	-	?
Treatment fidelity	-	+	+	-	?	?	?	?	-	-	+
Therapist qualifications	-	+	+	-	?	-	NA	+	-	-	?
Overall bias	-	+	?	-	-	-	?	?	-	-	?

+ = low risk of bias;— = high risk of bias;? = some risk of bias; NA = Not applicable due to self-administered intervention.