Incidence of umbilical vein catheter-associated thrombosis of the portal system: A systematic review and meta-analysis

Table 1 Risk of bias assessment (Newcastle-Ottawa scale for non-randomized studies)

Ref.	Selection	Comparability	Outcome	Total score
Levit et al[42], 2020	4	2	3	9
Dubbink-Verheij et al[31], 2020	4	2	3	9
Chen et al[15], 2020	4	0	3	7
Hwang et al[46], 2020	4	2	3	9
Çakır et al[38], 2020	4	0	3	7
Cabannes et al[32], 2018	4	2	3	9
Derinkuyu et al[5], 2018	4	0	3	7
Chandrashekhar et al[45], 2015	4	0	3	7
Michel et al[37], 2012	4	2	3	9
Gharehbaghi et al[39], 2011	4	2	3	9
Sakha et al[41], 2007	4	2	3	9
Turebylu et al[21], 2007	4	2	3	9
Kim et al[30], 2001	4	2	3	9
Boo et al[44], 1999	4	2	3	9
Schwartz et al[40], 1997	4	0	3	7
Yadav et al[43], 1993	4	0	2	6