Development and validation of a prognostic nomogram model for 28-day mortality based on IP-10 and clinical parameters in septic patients in the emergency department

Background Early identification and precise prognosis of sepsis are of great significance. Traditional biomarkers, such as procalcitonin (PCT) and lactate (Lac), do not reflect the immune dysregulation at the center of sepsis pathophysiology. Interferon - γ -induced protein 10 (IP-10) is an important chemokine for septic immune dysregulation responses and may have good predictive value. Our research aims to establish and validate a clinically applicable nomogram that combines IP-10 and conventional clinical parameters to predict the 28-day mortality in septic patients in the emergency department (ED). Methods This study recruited 655 patients who met the criteria of sepsis 3.0 from the ED of Beijing Chao-Yang Hospital from November 2023 to May 2025. A total of 580 patients were analyzed and randomly divided into the training group and the validation group in a 7:3 ratio. The variable selection in this study was conducted using the Least Absolute Shrinkage and Selection Operator (LASSO) regression, and our research employed multivariate logistic regression to determine independent predictors of 28-day mortality. The study scientifically evaluated nomogram using receiver operating characteristic (ROC) curves, calibration plots, Decision Curve Analysis (DCA), and Clinical Impact Curves (CIC). Results Among the 580 patients, the 28-day mortality rate was 12.9% (75 non-survivors). Multivariate analysis identified five independent risk factors: IP-10 (OR = 1.978, 95% CI: 1.964-1.992), Sequential Organ Failure Assessment (SOFA) score (OR = 1.526, 95% CI: 1.365-1.758), Lac (OR = 1.447, 95% CI: 1.281-1.711), PCT (OR = 1.562, 95% CI: 1.341-1.924), and Acute Physiology and Chronic Health Evaluation II (APACHE II) score (OR = 1.658, 95% CI: 1.515-1.840). The nomogram showed excellent discriminatory ability. The area under the curve (AUC) of the training set and validation set was 0.952 (95% CI: 0.930-0.974) and 0.946 (95% CI: 0.911-0.981), respectively. Calibration was satisfactory, and DCA/CIC analyses confirmed that within the risk threshold range, the clinical net benefit was significant. Conclusion It is the first time to develop and validate a prognostic nomogram model for 28-day mortality based on IP-10 and clinical parameters in septic patients in the ED. This tool may assist clinicians in early risk stratification and clinical decision-making.