Abstract:Objective To analyze the risk factors for delirium in elderly patients with severe sepsis using a nomogram model.Methods A retrospective analysis was conducted on clinical data from 308 elderly patients with severe sepsis treated in our hospital from October 2021 to October 2023. Delirium was assessed using the Confusion Assessment Method for the ICU (CAM-ICU), and patients were categorized into delirium (n = 103) and non-delirium (n = 205) groups based on the assessment results. Data collected included gender, age, education level, underlying diseases (hypertension, hyperlipidemia, coronary heart disease, hyperglycemia, hypoglycemia), severity of infection (severe sepsis, septic shock), complications (hypoxemia, hypoalbuminemia, acute kidney injury, acute respiratory distress syndrome), use of sedatives or mechanical ventilation, and basic biochemical indicators. The Sequential Organ Failure Assessment (SOFA) score and levels of inflammatory markers [C-reactive protein (CRP), interleukin-6 (IL-6), procalcitonin (PCT)], soluble protein 100β (S-100β), and homocysteine (Hcy) were compared between the two groups. Logistic regression analysis was used to identify risk factors for delirium, and a nomogram prediction model was developed to evaluate the model's fit.Results The delirium group was older, had higher SOFA scores, white blood cell counts, CRP, IL-6, PCT, S-100β, and Hcy levels (all P <0.05), and lower hemoglobin levels compared to the non-delirium group (P <0.05). Higher proportions of septic shock, hyperglycemia, hypoxemia, hypoalbuminemia, and hypercapnia, as well as the use of sedatives and mechanical ventilation, were observed in the delirium group (P <0.05). No significant differences were found in gender composition, BMI, smoking, alcohol use, hypertension, hyperlipidemia, coronary heart disease, acute kidney injury, acute respiratory distress syndrome, mechanical ventilation, continuous renal replacement therapy, lymphocyte counts, or creatinine levels (P >0.05). Logistic regression analysis identified age, septic shock, hyperglycemia, hypercapnia, hypoalbuminemia, use of sedatives, SOFA score, and levels of IL-6, S-100β, and Hcy as significant factors influencing the occurrence of delirium in elderly patients with severe sepsis (P <0.05). The calibration curve showed that the predictive model closely approximates the ideal curve, with a mean absolute error of 0.029, sensitivity of 79.6% (95% CI: 0.705, 0.869), specificity of 93.2% (95% CI: 0.888, 0.962), Youden's index of 0.718, and an AUC of 0.932 (95% CI: 0.904, 0.960).Conclusion The occurrence of delirium in elderly patients with severe sepsis is associated with multiple factors including age, blood sugar levels, nutritional status, severity of illness, treatment methods, and inflammation levels. Assessing these indicators can help in the early identification of delirium.