Table 3.

Trial- and individual patient–level surrogacy

True endpoint	No. of comparison units (No. of patientsa)	${\mathrm{R}}_{\text{WLS}}^2$ (95% CI)	${\mathrm{R}}_{\text{Copula}}^2$ (95% CI)	ρCopula (95% CI)	STE (HR)
All trials included
5-y OS	14 (19 279)	0.82 (0.67 to 0.98)	0.92 (0.83 to 1.00)	0.90 (0.90 to 0.91)	0.79
6-y OS	13 (17 020)	0.88 (0.70 to 1.00)	0.97 (0.93 to 1.00)	0.91 (0.90 to 0.91)	0.80
6.5-y OS	10 (11 382)	0.94 (0.81 to 1.00)	0.99 (0.97 to 1.00)	0.91 (0.90 to 0.91)	0.80
Excluding 1 small comparison (n < 100)
5-y OS	13 (19 181)	0.79 (0.58 to 1.00)	0.74 (0.49 to 0.98)	0.90 (0.90 to 0.91)	—
6-y OS	12 (16 922)	0.86 (0.60 to 1.00)	0.89 (0.78 to 1.00)	0.91 (0.90 to 0.91)	—
6.5-y OS	9 (11 284)	0.93 (0.67 to 1.00)	0.97 (0.94 to 1.00)	0.91 (0.90 to 0.91)	—

^a AVANT (14) trial included 2 experimental arms. The control arm patients (n = 901) were duplicated for surrogacy analyses. HR = hazard ratio; OS = overall survival; ρ_Copula = rank correlation coefficient; STE = surrogate threshold effect; WLS = weighted least squares.