Table 1.

Quality assessment of included studies. Newcastle–Ottawa scale quality analysis of 23 case–control studies on the relationship between SNP and cholangiocarcinoma [17].The maximum score of the scale is nine points, with studies being categorized as low (0–3 points), moderate (4–6 points) and high quality (7–9 points), respectively. (★) represents one point.

Author/Year/Ref.	Selection	Comparability	Outcomes	Quality Score
Chaiteerakij, 2015 [26]	★★★★	★★	★★★	9/9
Fingas, 2010 [27]	★★★★	★★	★★★	9/9
Hoblinger, 2009 [28]	★★★★	★	★★★	8/9
Honjo, 2005 [29]	★★★★	★	★★★	8/9
Khunluck, 2014 [30]	★★★★	★★	★★★	9/9
Ko, 2006 [31]	★★★★	★★	★★★	9/9
Krawczyk, 2013 [32]	★★★★	★★	★★★	9/9
Krawczyk, 2011 [19]	★★★	★	★★★	7/9
Lampropoulou, 2021 [33]	★★★★	★★	★★★	9/9
Melum, 2007 [34]	★★★★	★	★★★	8/9
Meng, 2014 [35]	★★★★	★	★★	7/9
Mihalache, 2012 [36]	★★★★	★★	★★★	9/9
Mihalache, 2011 [37]	★★★★	★★	★★★	9/9
Prawan, 2005 [38]	★★★★	★	★★★	8/9
Songserm, 2011 [39]	★★★★	★★	★★★	9/9
Sun, 2018 [40]	★★★★	★	★★★	8/9
Surapaitoon, 2017 [41]	★★★★	★★	★★★	9/9
Wadsworth, 2019 [21]	★★★★	★★	★★★	9/9
You, 2012 [42]	★★★★	★★	★★★	9/9
Zhao, 2014 [43]	★★★★	★★	★★★	9/9
Zeng, 2013 [22]	★★★★	★★	★★★★	9/9
Songserm, 2014 [44]	★★★★	★★	★★★★	9/9
Liu et al., 2022 [45]	★★★★	★★	★★★★	9/9
Hsing et al., 2008 [25]	★★★★	★★	★★★	8/9