Performance of Restricted Mean Survival Time Based Methods and Traditional Survival Methods: An Application in an Oncological Data

Table 2

Basic characteristics and univariable analyses including traditional methods and restricted mean survival time based methods.

Covariates	Description	Group comparison			Univariable regression
		Survival rate		Difference in RMST ^a	Cox regression ^b	RMST-based regression
		Log-rank	Wilcoxon			PV regression ^a	IPCW regression (individual weights) ^a	IPCW regression (group-specified weight) ^a
Age (continuous)	30 (19, 54)	—	—	—	1.13, <0.001	-4.09, <0.001	-4.35, <0.001	—
Age (binary)
>60 years	841(19.09%)	<0.001	<0.001	-146.64, <0.001	3.82, <0.001	-147.29, <0.001	-137.17, <0.001	-146.43, <0.001
< =60 years	3564(80.91%)	—	—	Reference	Reference	Reference	Reference	Reference
Sex
Male	2513(57.05%)	0.005	0.058	-24.31, 0.004	Time-varying	-24.22, 0.004	-60.12, 0.46	-23.98, 0.42
Female		—	—	Reference		Reference	Reference	Reference
Year of diagnosis
1970s~1980s	803 (18.23%)	<0.001	<0.001	-26.89, <0.001	1.32, <0.001	-28.03, <0.001	178.96, <0.001	-26.27, <0.001
1990s~2000s	3602(81.77%)	—	—	Reference	Reference	Reference	Reference	Reference
Race
White	3373(76.57%)	0.04	0.004	-12.60, 0.21	Time-varying	-12.15, 0.21	-40.21, 0.71	-12.80, 0.74
Others	1032(23.43%)	—	—	Reference		Reference	Reference	Reference
Tumor size		<0.001	<0.001	<0.001
>100 mm	209(4.74%)	—	—	-50.03, <0.001	Time-varying	-58.56, <0.001	-33.62, 0.010	-50.02, 0.07
Unknown	3541(80.39%)	—	—	-36.45, <0.001	Time-varying	-39.35, <0.001	72.64, <0.001	-37.02, <0.001
<100 mm	655(14.87%)	—	—	—			Reference	Reference
Extend of disease		<0.001	<0.001	<0.001
Metastasis	887(20.14%)	—	—	-164.09, <0.001	6.34, <0.001	-183.43, <0.001	-113.45, <0.001	-164.05, <0.001
Local invasion	261(5.93%)	—	—	-60.15, <0.001	1.98, <0.001	-71.54, <0.001	-22.99, <0.001	-60.18, <0.001
Unknown	2974(67.51%)	—	—	-82.28, <0.001	2.50, <0.001	-93.62, <0.001	2.21, <0.001	-82.94, <0.001
Confined	283(6.42%)	—	—	Reference	Reference	Reference	Reference	Reference
AJCC		<0.001	<0.001	<0.001
III + IV	421(9.56%)	—	—	-84.75, <0.001	Time-varying	-74,77, <0.001	-67.47, <0.001	-84.90, <0.001
II	886(20.11%)	—	—	-33.62, <0.001	Time-varying	-26.51, <0.001	-41.22, <0.001	-33.82, <0.001
Unknown	2891(65.63%)	—	—	-45.51, <0.001	Time-varying	-38.16, <0.001	-3.95, 0.11	-45.40, <0.001
I	207(4.07%)	—	—	Reference		Reference	Reference	Reference
Surgery, yes	3427(77.80%)	<0.001	<0.001	121.41, <0.001	0.37, <0.001	121.11, <0.001	18.17, 0.88	121.05, <0.001
Radiation, yes	621(14.10%)	<0.001	<0.001	-133.53, <0.001	2.54, <0.001	-134.41, <0.001	-29.15, 0.73	-133.39, <0.001
Chemotherapy, yes	2959(67.17%)	<0.001	<0.001	16.26, 0.048	Time-varying	17.04, 0.05	-137.623, 0.001	16.06, 0.27

RMST, restricted mean survival time. IPCW, inverse probability of censored weighting. AJCC, American Joint Committee on Cancer for staging. ^a Presented as point estimation of coefficient (difference in RMST) and corresponding value. ^b Presented as point estimation of hazard ratio and corresponding value or “time-varying”. . Overall test for categorical covariates with more than 2 groups.