Cell-free DNA liquid biopsy for early detection of gastrointestinal cancers: A systematic review

Table 3 Risk of bias of included studies, determined using the ROBINS-I tool (2016)

Ref.		Entry	Judgement	Support for judgement
Li et al[13]	A	Bias due to confounding	Low risk	No confounding factors
	B	Bias in selection of participants into the study	No information	No information about the start of follow up and intervention for the participants
	C	Bias in classification of interventions	No information	No information about the start of follow up and intervention for the participants
	D	Bias due to deviationsfrom intended interventions	Low risk	No deviations from the planned interventions
	E	Bias due to missing data	Low risk	All data were reported
	F	Bias in measurement of outcomes	Low risk	Comparable methods of outcome assessment in the groups, intervention received in each group unlikely to influence the outcome measure, any error in measuring the outcome is unrelated to intervention
	G	Bias in selection of the reported result	Moderate risk	No pre-registered protocol available; outcome measurements and analyses consistent with a priori plan
Chen et al[14]	A	Bias due to confounding	Low risk	No confounding factors
	B	Bias in selection of participants into the study	Low risk	Information provided about the start of follow up and intervention for the participants
	C	Bias in classification of interventions	Low risk	Information provided about the start of follow up and intervention for the participants
	D	Bias due to deviationsfrom intended interventions	Low risk	No deviations from the planned interventions
	E	Bias due to missing data	Low risk	All data were reported
	F	Bias in measurement of outcomes	Low risk	Comparable methods of outcome assessment in the groups, intervention received in each group unlikely to influence the outcome measure, any error in measuring the outcome is unrelated to intervention
	G	Bias in selection of the reported result	Moderate risk	No pre-registered protocol available; outcome measurements and analyses consistent with a priori plan
Guler et al[18]	A	Bias due to confounding	Low risk	No confounding factors
	B	Bias in selection of participants into the study	No information	No information about the start of follow up and intervention for the participants
	C	Bias in classification of interventions	No information	No information about the start of follow up and intervention for the participants
	D	Bias due to deviationsfrom intended interventions	Low risk	No deviations from the planned interventions
	E	Bias due to missing data	Low risk	All data were reported
	F	Bias in measurement of outcomes	Low risk	Comparable methods of outcome assessment in the groups, intervention received in each group unlikely to influence the outcome measure, any error in measuring the outcome is unrelated to intervention
	G	Bias in selection of the reported result	Moderate risk	No pre-registered protocol available; outcome measurements and analyses consistent with a priori plan
Junca et al[12]	A	Bias due to confounding	Low risk	No confounding factors
	B	Bias in selection of participants into the study	No information	No information about the start of follow up and intervention for the participants
	C	Bias in classification of interventions	No information	No information about the start of follow up and intervention for the participants
	D	Bias due to deviationsfrom intended interventions	Low risk	No deviations from the planned interventions
	E	Bias due to missing data	Low risk	All data were reported
	F	Bias in measurement of outcomes	Low risk	Comparable methods of outcome assessment in the groups, intervention received in each group unlikely to influence the outcome measure, any error in measuring the outcome is unrelated to intervention
	G	Bias in selection of the reported result	Moderate risk	No pre-registered protocol available; outcome measurements and analysesconsistent with a priori plan
Tao et al[15]	A	Bias due to confounding	Low risk	No confounding factors
	B	Bias in selection of participants into the study	Low risk	Information provided about the start of follow up and intervention for the participants in the supplementary materials
	C	Bias in classification of interventions	Low risk	Information provided about the start of follow up and intervention for the participants in the supplementary materials
	D	Bias due to deviationsfrom intended interventions	Low risk	No deviations from the planned interventions
	E	Bias due to missing data	Low risk	All data were reported
	F	Bias in measurement of outcomes	Low risk	Comparable methods of outcome assessment in the groups, intervention received in each group unlikely to influence the outcome measure, any error in measuring the outcome is unrelated to intervention
	G	Bias in selection of the reported result	Moderate risk	No pre-registered protocol available; outcome measurements and analyses consistent with a priori plan
Cristiano et al[19]	A	Bias due to confounding	Low risk	No confounding factors
	B	Bias in selection of participants into the study	No information	No information about the start of follow up and intervention for the participants
	C	Bias in classification of interventions	No information	No information about the start of follow up and intervention for the participants
	D	Bias due to deviationsfrom intended interventions	Low risk	No deviations from the planned interventions
	E	Bias due to missing data	Low risk	All data were reported
	F	Bias in measurement of outcomes	Low risk	Comparable methods of outcome assessment in the groups, intervention received in each group unlikely to influence the outcome measure, any error in measuring the outcome is unrelated to intervention
	G	Bias in selection of the reported result	Moderate risk	No pre-registered protocol available; outcome measurements and analyses consistent with a priori plan
Li et al[17]	A	Bias due to confounding	Low risk	No confounding factors
	B	Bias in selection of participants into the study	No information	No information about the start of follow up and intervention for the participants
	C	Bias in classification of interventions	No information	No information about the start of follow up and intervention for the participants
	D	Bias due to deviationsfrom intended interventions	Low risk	No deviations from the planned interventions
	E	Bias due to missing data	Low risk	All data were reported
	F	Bias in measurement of outcomes	Low risk	Comparable methods of outcome assessment in the groups, intervention received in each group unlikely to influence the outcome measure, any error in measuring the outcome is unrelated to intervention
	G	Bias in selection of the reported result	Moderate risk	No pre-registered protocol available; outcome measurements and analyses consistent with a priori plan
Qu et al[16]	A	Bias due to confounding	Low risk	No confounding factors
	B	Bias in selection of participants into the study	Low risk	Information provided about the start of follow up and intervention for the participants
	C	Bias in classification of interventions	Low risk	Information provided about the start of follow up and intervention for the participants
	D	Bias due to deviationsfrom intended interventions	Low risk	No deviations from the planned interventions
	E	Bias due to missing data	Low risk	All data were reported
	F	Bias in measurement of outcomes	Low risk	Comparable methods of outcome assessment in the groups, intervention received in each group unlikely to influence the outcome measure, any error in measuring the outcome is unrelated to intervention
	G	Bias in selection of the reported result	Low risk	Pre-registered protocol available (NCC201709011)
Cai et al[11]	A	Bias due to confounding	Low risk	No confounding factors
	B	Bias in selection of participants into the study	Low risk	Information provided about the start of follow up and intervention for the participants
	C	Bias in classification of interventions	Low risk	Information provided about the start of follow up and intervention for the participants
	D	Bias due to deviationsfrom intended interventions	Low risk	No deviations from the planned interventions
	E	Bias due to missing data	Low risk	All data were reported
	F	Bias in measurement of outcomes	Low risk	Comparable methods of outcome assessment in the groups, intervention received in each group unlikely to influence the outcome measure, any error in measuring the outcome is unrelated to intervention
	G	Bias in selection of the reported result	Moderate risk	No pre-registered protocol available; outcome measurements and analyses consistent with a priori plan
Wan et al[9]	A	Bias due to confounding	Low risk	No confounding factors
	B	Bias in selection of participants into the study	No information	No information about the start of follow up and intervention for the participants
	C	Bias in classification of interventions	No information	No information about the start of follow up and intervention for the participants
	D	Bias due to deviationsfrom intended interventions	Low risk	No deviations from the planned interventions
	E	Bias due to missing data	Low risk	All data were reported
	F	Bias in measurement of outcomes	Low risk	Comparable methods of outcome assessment in the groups, intervention received in each group unlikely to influence the outcome measure, any error in measuring the outcome is unrelated to intervention
	G	Bias in selection of the reported result	Moderate risk	No pre-registered protocol available; outcome measurements and analyses consistent with a priori plan
Jensen et al[20]	A	Bias due to confounding	Low risk	No confounding factors
	B	Bias in selection of participants into the study	Low risk	Information provided about the start of follow up and intervention for the participants
	C	Bias in classification of interventions	Low risk	Information provided about the start of follow up and intervention for the participants
	D	Bias due to deviationsfrom intended interventions	Low risk	No deviations from the planned interventions
	E	Bias due to missing data	Low risk	All data were reported
	F	Bias in measurement of outcomes	Low risk	Comparable methods of outcome assessment in the groups, intervention received in each group unlikely to influence the outcome measure, any error in measuring the outcome is unrelated to intervention
	G	Bias in selection of the reported result	Moderate risk	No pre-registered protocol available; outcome measurements and analyses consistent with a priori plan
Nunes et al[21]	A	Bias due to confounding	Low risk	No confounding factors
	B	Bias in selection of participants into the study	No information	No information about the start of follow up and intervention for the participants
	C	Bias in classification of interventions	No information	No information about the start of follow up and intervention for the participants
	D	Bias due to deviationsfrom intended interventions	Low risk	No deviations from the planned interventions
	E	Bias due to missing data	Low risk	All data were reported
	F	Bias in measurement of outcomes	Low risk	Comparable methods of outcome assessment in the groups, intervention received in each group unlikely to influence the outcome measure, any error in measuring the outcome is unrelated to intervention
	G	Bias in selection of the reported result	Moderate risk	No pre-registered protocol available; outcome measurements and analyses consistent with a priori plan
Perrone et al[22]	A	Bias due to confounding	Low risk	No confounding factors
	B	Bias in selection of participants into the study	Low risk	Information provided about the start of follow up and intervention for the participants
	C	Bias in classification of interventions	Low risk	Information provided about the start of follow up and intervention for the participants
	D	Bias due to deviationsfrom intended interventions	Low risk	No deviations from the planned interventions
	E	Bias due to missing data	Low risk	All data were reported
	F	Bias in measurement of outcomes	Low risk	Comparable methods of outcome assessment in the groups, intervention received in each group unlikely to influence the outcome measure, any error in measuring the outcome is unrelated to intervention
	G	Bias in selection of the reported result	Moderate risk	No pre-registered protocol available; outcome measurements and analyses consistent with a priori plan