Table 2.

Harell's c‐indices for five risk scores, DEL biology, and the combination of the NCCN‐IPI and DEL biology

	PFS		OS
Risk model	Harell's c	95%CI	Harell's c	95%CI
IPI	0.59	0.49‐0.69	0.63	0.53‐0.73
R‐IPI	0.59	0.49‐0.69	0.63	0.53‐0.73
NCCN‐IPI	0.61	0.51‐0.71	0.66	0.55‐0.76
MSKCC	0.59	0.49‐0.69	0.61	0.51–0.71
IELSG	0.54	0.45‐0.64	0.57	0.47‐0.66
DEL	0.73	0.65‐0.81	0.72	0.64‐0.80
NCCN‐IPI + DEL	0.76	0.67‐0.84	0.76	0.67‐0.85

Note: Data are reported for the PFS and OS endpoint separately. Harell's c‐index quantifies discrimination, that is, the probability that among two randomly selected patients of whom one will develop the outcome and one will not develop the outcome the one with the outcome will have a higher value of the predictor variable. Harell's c‐indices range from 0 to 1, with 0.5 indicating a discriminator that is not better than chance.

Abbreviations: 95%CI, 95% confidence interval; DEL, double expressor lymphoma; IELSG, International Extranodal Lymphoma Study Group risk score for PCNSL outcomes (without cerebrospinal fluid); IPI, International Prognostic Index; MSKCC, Memorial Sloan Kettering Cancer Centre risk score for PCNSL outcomes; NCCN‐IPI, National Comprehensive Cancer Network International Prognostic Index; OS, overall survival;PFS, progression‐free survival; R‐IPI, Revised International Prognostic Index.