Table 6 Bootstrap validation according... | American Society of Hematology

Table 6

Bootstrap validation according to Efron et al³¹

Model	Method	Log rank-χ²	df	c	SEP
Cox model	optimistic	55.84*	4	0.6867	1.00†
Cox model	bootstrap	46.62*	4	0.6791	0.91†
MIPI	optimistic	61.11	2	0.6668	1.59
MIPI	bootstrap	47.64	2	0.6536	1.49
MIPI_b	optimistic	39.78	2	0.7096	1.74
MIPI_b	bootstrap	31.78	2	0.6962	1.58
Risk groups using standard cutpoints	optimistic	34.77	2	0.6393	1.51
Simplified MIPI	optimistic	63.15	2	0.6716	1.60
IPI	external	38.83	3	0.6359	1.41
IPI LR/LIR vs HI vs HR	external	35.36	2	0.6149	1.40
IPI LR vs LI/HI vs HR	external	35.10	2	0.6170	1.31
IPI LR vs LI vs HI/HR	external	24.22	2	0.6178	1.41
FLIPI	external	14.14	2	0.5773	1.36

Model	Method	Log rank-χ²	df	c	SEP
Cox model	optimistic	55.84*	4	0.6867	1.00†
Cox model	bootstrap	46.62*	4	0.6791	0.91†
MIPI	optimistic	61.11	2	0.6668	1.59
MIPI	bootstrap	47.64	2	0.6536	1.49
MIPI_b	optimistic	39.78	2	0.7096	1.74
MIPI_b	bootstrap	31.78	2	0.6962	1.58
Risk groups using standard cutpoints	optimistic	34.77	2	0.6393	1.51
Simplified MIPI	optimistic	63.15	2	0.6716	1.60
IPI	external	38.83	3	0.6359	1.41
IPI LR/LIR vs HI vs HR	external	35.36	2	0.6149	1.40
IPI LR vs LI/HI vs HR	external	35.10	2	0.6170	1.31
IPI LR vs LI vs HI/HR	external	24.22	2	0.6178	1.41
FLIPI	external	14.14	2	0.5773	1.36

df indicates degrees of freedom; c, Harrell measure of concordance³⁴ between expected and observed survival times; SEP, measure of separation³⁵ of survival curves; standard cutpoints: 60 years of age, upper limit of normal for LDH, 10 × 10⁹ leukocytes/L; optimistic, estimation using the data set of model development; bootstrap, estimation corrected for overoptimism; and external, estimation using an independent data set.

Likelihood ratio statistic.

†

Calibration slope: regression coefficient of the prognostic score.

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