Risk factor analysis and nomogram model construction for mortality in patients following colonic perforation surgery

Figure 3 Dual-cut-off funnel validation. A: Confusion matrix (high-sensitivity cut-off of 0.020). Confusion matrix for the entire cohort (n = 134) at the screening threshold of 0.020. The model correctly identified 20 of 21 deaths (sensitivity = 95.2%) with only one false-negative case, achieving a negative predictive value of 95.8% and supporting its use as a high-sensitivity screening criterion; B: Funnel pathway diagram. Flow chart of the dual-cut-off funnel strategy. Step 1 (≥ 0.020) flagged 92 high-risk patients (68.7%). Step 2 (≥ 0.121) confirmed 17 for intensive intervention while downgrading 75 to standard care, reducing advanced resource use by 53% in this cohort.