Helicobacter pylori virulence gene expression defines a stage-associated transcriptional signature in gastric cancer

Table 9 Stage-associated transcriptional signature validation and correlation analysis (n = 159)

Parameter/variable	Spearman (ρ)	P value	VIF	ROC-AUC (95%CI)	Directional trend/validation
babA	-0.467	< 0.001b	1.05	0.702 (0.632-0.795)	Downregulation
iceA	-0.133	0.155	1.00	0.584 (0.540-0.717)	Variable
cagA	0.122	0.126	1.05	0.612 (0.453-0.645)	Upregulation
vacA	-0.010	0.210	1.10	0.528 (0.457-0.647)	Neutral
Combined model (apparent, full-cohort)	ρ = 0.494	< 0.001b	1.02	0.769	Linear fit
Combined model (Nested 5-fold CV)	-	-	-	0.747 (0.664-0.823)	Calibration: Hosmer-Lemeshow χ2 = 5.53, df = 3, P > 0.05
5-fold cross-validation (Cauchit)	-	-	-	-	Accuracy: 0.535; Kappa: 0.325
CART - decision tree (apparent, full-cohort)	-	-	-	0.867	Sensitivity: 74.5%; specificity: 81.7%
CART - decision tree (Nested 5-fold CV)	-	-	-	0.68 (95%CI: 0.59-0.77)	Sensitivity: 54.5%; specificity: 75.0%

^bP < 0.01.

cagA: Cytotoxin-associated gene A; vacA: Vacuolating cytotoxin A; babA: Blood group antigen-binding adhesin A; iceA: Induced by contact with epithelium gene A; VIF: Variance inflation factor; ROC: Receiver operating characteristic; AUC: Area under the curve; CART: Classification and regression tree; CV: Cross-validation.