Table 2. Meta-regression and subgroup analysis of the studies reporting the association of LINE-1 hypomethylation and overall survival of cancer patients.

Stratified study	No. of studies	No. of patients	Fixed-Model (HR, 95%CI)	Random-Model (HR, 95%CI)	Meta-regression p value (%)	HG I2 (%)	HG p-value
Year					0.362
<2011	7	1342	1.40(1.10,1.77)	1.46(0.83,2.58)		77.5	0.001
> = 2011	12	2247	1.88(1.57,2.24)	2.09(1.51,2.91)		56.9	0.006
Hypomethylation cut-off					0.603
Dichotomy	16	2886	1.65(1.37,1.98)	1.76(1.22,2.52)		67.5	0.001
Quartile	3	703	1.76(1.40,2.20)	2.15(1.25,3.71)		73.3	0.001
Hypomethylation rate					0.067
< = 50%	7	1010	1.92(1.57,2.35)	2.52(1.72,3.71)		54.2	0.033
>50%	12	2579	1.48(1.21,1.82)	1.40(0.92,2.14)		71.8	0.001
Study race					0.300
Yellow	12	1729	1.76(1.47,2.11)	2.08(1.50,2.89)		55.8	0.035
White	7	1860	1.59(1.26,2.00)	1.57(0.97,2.53)		72.4	0.001
Age					0.423
< = 60	9	123	1.52(1.27,1.82)	0.33(0.10,0.76)		73.7	0.001
>60	9	3438	1.86(1.45,2.72)	1.93(1.44,2.58)		15.9	0.308
Method					0.759
Pyrosequencing	12	2365	1.90(1.57,2.30)	0.54(0.15,0.93)		60.8	0.003
Others	7	1224	1.45.(1.17.,1.80)	1.70(0.96,3.02)		73.2	0.001
Bio-samples					0.304
Tissue	16	2617	1.61(1.38,1.87)	1.55(1.11,0.93)		69.3	0.001
Blood	3	972	2.84(1.76,4.59)	2.84(1.76,4.59)		0.00	0.948
REMARK Score					0.728
<17	10	1191	1.73(1.24,2.42)	1.66(1.16,1.88)		66.6	0.01
> = 17	9	2398	1.68(1.44,1.97)	1.89(1.36,2.62)		69.1	0.001
No. of patients					0.536
>200	9	1031	1.68(1.31,2.17)	1.65(1.00,2.70)		66.1	0.001
<200	10	2558	1.69(1.43,2.01)	1.99(1.38,2.87)		71.3	0.001
Types of cancers					0.972
digestive system,	8	2873	1.89(1.50,2.39)	2.07(1.24,3.44)		74	0.001
respiratory system tumors	3	789	1.40(1.04,1.88)	1.35(0.82,2.23)		64.1	0.061
other tumors	8	1384	1.70(1.36,2.13)	1.95(1.13,3.39)		63.1	0.008

Abbreviations: CI = confidence interval; HR = hazard ration; HG: heterogeneity.