Table 4.

Risk of bias of nonrandomized studies using ROBINS-I tool

Bias Domain		Bathen et al42	Ferrell et al21	Hakimi et al43	Liaghat et al40	To & Alexander39
Bias because of confounding	1.1	Y	Y	Y	Y	Y
	1.2	NA	NA	Y	NA	N
	1.3	NA	NA	Y	NA	N
	1.4	N	NA	NA	NA	Y
	1.5	NA	NA	NA	NA	N
	1.6	NA	NA	NA	NA	NA
	1.7	NA	NA	N	NA	NA
	1.8	NA	NA	N	NA	NA
	RoB judgment	Critical	Critical	Critical	Critical	Moderate
Bias in selection of participants into the study	2.1	N	N	N	N	N
	2.2	NA	NA	NA	NA	NA
	2.3	NA	NA	NA	NA	NA
	2.4	Y	PN	Y	Y	Y
	2.5	NA	N	NA	NA	NA
	RoB judgment	Low	Serious	Low	Low	Low
Bias in classification of interventions	3.1	Y	PY	N	Y	Y
	3.2	Y	Y	NI	y	Y
	3.3	PN	PY	NI	PN	N
	RoB judgment	Low	Moderate	Serious	Low	Low
Bias because of deviations from intended interventions	4.1	N	NI	NI	N	N
	4.2	NA	NA	NI	NA	NA
	4.3	Y	NI	NI	NI	NA
	4.4	Y	NI	NI	Y	Y
	4.5	PY	NI	NI	PY	N
	4.6	NA	NI	NI	NA	Y
	RoB judgment	Low	Serious	NI	Moderate	Moderate
Bias because of missing data	5.1	Y	N	N	N	N
	5.2	PN	Y	Y	N	N
	5.3	PN	N	NI	N	N
	5.4	NA	NA	N	NA	N
	5.5	NA	N	N	Y	Y
	RoB judgment	Low	Serious	Critical	Moderate	Moderate
Bias in measurement of outcomes	6.1	PY	PY	N	PY	N
	6.2	PY	Y	N	Y	Y
	6.3	Y	PY	Y	Y	Y
	6.4	PN	PN	N	PN	N
	RoB judgment	Serious	Serious	Low	Moderate	Moderate
Bias in selection of reported results	7.1	PN	PN	N	N	N
	7.2	PN	PN	N	N	N
	7.3	N	N	N	N	N
	RoB judgment	Low	Low	Low	Low	Low
Overall bias: low/moderate/serious/critical/NI		Critical	Critical	Critical	Critical	Moderate

Abbreviations: N, no; NA, not applicable; NI, no information; PN, probably no; PY, probably yes; RoB; risk of bias; Y, yes.