Table 2. Subgroup analyses of the prognostic effect of Tregs.

Subgroup	Number of Studies	Test for association			Test for heterogeneity
		HR	95% CI	p	Chi2	I2	p
OS
Therapy
Resection	13	2.03	[1.76, 2.35]	< 0.00001	14.08	15%	0.30
TACE	2	2.02	[1.58, 2.59]	< 0.00001	0.05	0%	0.44
Trial design
Retrospective cohort	15	1.97	[173, 2.24]	< 0.00001	17.48	20%	0.23
Prospective cohort	3	1.61	[1.14, 2.26]	0.007	1.96	0%	0.38
Method of detection
Immunohistochemistry	13	2.02	[1.69, 2.42]	< 0.00001	16.91	29%	0.15
Flow Cytometry	4	2.08	[1.65, 2.63]	< 0.00001	2.34	0%	0.51
PCR	1	2.86	[1.05, 7.79]	0.04	−	−	−
DFS
Therapy
Resection	14	1.89	[1.66, 2.15]	< 0.00001	8.88	0%	0.78
Liver transplantation	1	1.09	[0.12, 9.90]	0.94	−	−	−
Cryoablation	1	9.17	[2.47, 34.43]	0.0009	−	−	−
Trial design
Retrospective cohort	15	1.82	[1.61, 2.05]	< 0.00001	9.96	0%	0.77
Prospective cohort	2	3.86	[0.92, 16.23]	0.07	4.15	76%	0.04
Method of detection
Immunohistochemistry	14	1.81	[1.58, 2.08]	< 0.00001	6.51	0%	0.93
Flow Cytometry	3	2.47	[1.38, 4.41]	0.002	9.05	78%	0.01

OS, overall survival; DFS, disease-free survival; TACE, transhepatic arterial chemotherapy and embolization; PCR, polymerase chain reaction.