External validation of the Bayesian Estimated Tools for Survival (BETS) models in patients with surgically treated skeletal metastases

Table 1 Comparison of categorical features between the training and validation sets

Feature		Training set (n = 189)		Validation set (n = 815)			P
Feature		No. of patients	%	No. of patients	%	% Missing	P
Sex^†‡	male	85	45.0	369	45.3	0	.91
Sex^†‡	female	104	55.0	446	54.7	0	.91
Oncologic diagnosis grouping^†‡	1.0	52	27.3	173	21.3	0.4	.001*
	2.0	34	18.2	74	9.2
	3.0	103	54.5	567	69.1
Visceral metastases^†‡	yes	114	60.3	325	39.8	6.1	<.0001*
Visceral metastases^†‡	no	75	39.7	441	54.1	6.1	<.0001*
Lymph node metastases^†‡	yes	36	18.8	169	20.7	61.8	<.0001*
Lymph node metastases^†‡	no	153	81.2	143	17.5	61.8	<.0001*
Skeletal metastases^†‡	solitary	55	29.0	123	15.1	3.2	<.0001*
Skeletal metastases^†‡	multiple	134	71.0	666	81.7	3.2	<.0001*
Pathologic fracture status^†‡	yes	84	44.2	614	75.3	0.7	<.0001*
Pathologic fracture status^†‡	no	105	55.8	196	24.0	0.7	<.0001*
ECOG performance status^†‡	0,1,2	93	49.2	558	68.5	0	<.0001*
ECOG performance status^†‡	3,4	96	50.8	257	31.5	0	<.0001*
Survival > 3 months^†	yes	129	68.3	557	68.3	0	.78
Survival > 3 months^†	no	60	31.7	258	31.7	0	.78
Survival > 12 months^‡	yes	79	41.8	241	29.6	0	.002*
Survival > 12 months^‡	no	110	58.2	574	70.4	0	.002*

ECOG indicates Eastern Cooperative Oncology Group; % Missing, the proportion of unknown or missing data within the validation set.
*Distributions are significantly different between the training and validation sets by the chi-square· method.
^†Denotes feature of 3-month model.
^‡Denotes feature of 12-month model.

ISSN: 1471-2407