Prognostic role of the systemic immune-inflammation index in biliary tract cancers: a meta-analysis of 3,515 patients

Table 3 Subgroup analysis of the prognostic effect of SII for RFS/PFS in patients with BTC

Subgroups	No. of studies	No. of patients	HR (95%CI)	p	Effects model	Heterogeneity
Subgroups	No. of studies	No. of patients	HR (95%CI)	p	Effects model	I²(%)	Ph
Total	6	1666	1.66 (1.38–1.99)	<0.001	Fixed	1.4	0.407
Countries
Asian	4	746	1.71 (1.33–2.19)	<0.001	Fixed	28.6	0.241
Non-Asian	2	920	1.60 (1.23–2.09)	0.001	Fixed	0	0.384
Sample size
≤140	3	216	2.34 (1.58–3.46)	<0.001	Fixed	0	0.955
>140	3	1450	1.51 (1.23–1.85)	<0.001	Fixed	0	0.539
Histology
BTC	1	60	2.13 (0.99–4.57)	0.054	-	-	-
ECC	1	232	1.31 (0.77–2.22)	0.314	-	-	-
ICC	4	1374	1.69 (1.38–2.06)	<0.001	Fixed	22.6	0.275
TNM stage
I–III	3	1346	1.63 (1.32–2.01)	<0.001	Fixed	20.5	0.284
I–IV	1	232	1.31 (0.77–2.22)	0.314	Fixed	-	-
IV	2	88	2.32 (1.39–3.86)	0.001	Fixed	0	0.765
Treatment
Surgery	5	1606	1.64 (1.36–1.97)	<0.001	Fixed	13.9	0.325
Non-surgery	1	60	2.13 (0.99–4.57)	0.054	-	-	-
Cut-off value
≤600	3	790	1.48 (1.15–1.91)	0.002	Fixed	22.9	0.273
>600	3	876	1.87 (1.44–2.42)	<0.001	Fixed	0	0.622
Survival analysis
Multivariate	4	1374	1.69 (1.38–2.06)	<0.001	Fixed	22.6	0.275
Univariate	2	292	1.53 (0.99–2.36)	0.054	Fixed	3.6	0.308

BTC Biliary tract cancer, ECC Extrahepatic cholangiocarcinoma, ICC Intrahepatic cholangiocarcinoma, PFS Progression-free survival, RFS Recurrence-free survival

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