Gray’s Time-Varying Coefficients Model for Posttransplant Survival of Pediatric Liver Transplant Recipients with a Diagnosis of Cancer

Table 2

Estimated log hazard ratios for testing overall covariate effects and the test results of nonproportionality (nonprop) using Cox proportional hazards (PH) model and Gray piecewise constant time-varying coefficients (PC-TVC) model.

Covariate	Cox PH		Gray PC-TVC
	Log hazard ratio (95% CI)	𝑃 value	𝑃 value	Nonprop*𝑃 value
Donor blood type
A	−0.711 (−1.484, 0.062)	0.071	0.163	0.498
B	−0.343 (−1.534, 0.847)	0.572	0.679	0.480
AB	0.482 (−1.208, 2.171)	0.576	0.001	0.001
Serum creatinine (mg/dL)	1.635 (0.695, 2.575)	0.001	0.001	0.527
On ventilator	0.828 (−0.166, 1.821)	0.102	0.002	0.012
Positive CMV	0.686 (0.096, 1.275)	0.023	0.017	0.163
Female gender	−0.143 (−0.731, 0.445)	0.633	0.045	0.007

*Null hypothesis: the proportional hazards (PH) assumption is not violated.