Early Prediction and Prognostic Value of Chronic Critical Illness and Persistent Inflammation, Immunosuppression, and Catabolism Syndrome in Patients with Severe Acute Pancreatitis: A Retrospective Cohort Study

Background: Patients with severe acute pancreatitis (SAP) are at high risk for developing chronic critical illness (CCI) and persistent inflammation, immunosuppression, and catabolism syndrome (PICS). However, the specific risk factors and prognostic implications of these conditions remain unclear. Methods: This single-center retrospective cohort study enrolled adult patients with SAP requiring ICU stay > 14 days. Least absolute shrinkage and selection operator (LASSO) regression was used to select risk factors, followed by multivariable logistic regression to identify independent predictors for CCI and PICS. Discriminative ability of early severity scores was assessed using the area under the curve (AUC) and compared via the DeLong’s test. Kaplan–Meier and Cox regression evaluated in-hospital and 90-day mortality differences. Results: Among 156 SAP patients, 60 (38.5%) developed CCI, 38 (24.4%) progressed to PICS, and 32 (20.5%) met both criteria. After multivariable adjustment and sensitivity analyses, the computed tomography severity index (CTSI) emerged as an independent risk factor for both CCI (odds ratio [OR]: 1.40, 95% confidence interval [CI] 1.18–1.66) and PICS (OR: 1.56, 95% CI 1.29–1.89), with AUC values of 0.747 and 0.804, respectively. Significant differences in both the in-hospital and 90-day mortality rates were observed among the three groups (p < 0.001). The patients meeting both CCI and PICS criteria exhibited markedly increased risks of in-hospital (hazard ratio [HR]: 7.80, 95% CI 1.53–39.77; p = 0.013) and 90-day mortality (HR: 3.11, 95% CI 1.08–8.95; p = 0.035) after the multivariable adjustment. Conclusions: CTSI is an independent risk factor for CCI and PICS in patients with SAP. Both CCI and PICS were associated with a heightened risk of adverse outcomes. Future studies are warranted to explore the clinical characteristics and targeted interventions for this high-risk subgroup.