Clinical decision support for precolonoscopy cancer triage: A rule-out-oriented machine learning model for colorectal cancer risk

Table 5 Direction of feature effects in the SHapley Additive exPlanations summary

Feature (Figure 3)	Global direction1	Spearman ρ	High-tail direction2	Pos(SHAP) > 0 in top 20%
Glucose (mg/dL)	Increases	0.718	Decreases	0.234
Platelet (103/μL)	Increases	0.640	Decreases	0.137
SII	Increases	0.490	Decreases	0.019
Age (years)	Increases	0.424	Decreases	0.006
AST (U/L)	Increases	0.377	Decreases	0.216
NLR	Increases	0.368	Increases	0.931
HDL (mg/dL)	Decreases	-0.133	Decreases	0.142
ALT (U/L)	Decreases	-0.187	Decreases	0.000
NHR	Decreases	-0.263	Decreases	0.143
Neutrophil (103/μL)	Decreases	-0.525	Decreases	0.031

¹Global direction was defined by the sign of Spearman correlation between the feature value and its SHapley Additive exPlanations value (positive = higher values tend to increase the predicted malignancy probability; negative = higher values tend to decrease it).

²High-tail direction summarizes SHapley Additive exPlanations sign behavior among observations in the top 20% of the feature distribution, highlighting potential non-linear or threshold effects.

SHAP: SHapley Additive exPlanations; SII: Systemic immune-inflammation index; ALT: Alanine aminotransferase; NLR: Neutrophil to lymphocyte ratio; HDL: High-density lipoprotein; AST: Aspartate aminotransferase; NHR: Neutrophil-to-high-density lipoprotein ratio.