Tumor-resident microorganisms as clinical biomarkers in primary liver cancer: A systematic review of current evidence

Table 1 Newcastle-Ottawa Scale quality assessment of included studies

Ref.	Selection (0-4)	Comparability (0-2)	Outcome (0-3)	Total score
Chai et al[31]	4	2	3	9
Chakladar et al[20]	4	1	3	8
Xue et al[8]	4	2	1	7
Chen et al[15]	4	1	2	7
He et al[21]	4	2	3	9
Huang et al[22]	4	2	3	9
Jiang et al[16]	4	2	3	9
Komiyama et al[32]	4	2	3	9
Liu et al[24]	3	1	2	6
Liu et al[23]	4	2	3	9
Lu et al[25]	4	2	3	9
Qu et al[33]	4	2	3	9
Schulz et al[26]	4	1	3	8
Shen et al[27]	4	2	3	9
Song et al[17]	3	1	3	7
Sun et al[28]	4	2	3	9
Sun et al[29]	3	2	1	6
Wang et al[11]	4	2	3	9
Xin et al[34]	4	2	3	9
Yang et al[30]	4	2	2	8

Selection (0-4 points): Representativeness of exposed cohort, selection of non-exposed cohort, ascertainment of exposure, demonstration that outcome was not present at start of study. Comparability (0-2 points): Comparability of cohorts based on design or analysis. Outcome (0-3 points): Assessment of outcome, adequacy of follow-up length, adequacy of follow-up completeness.