Optimization of modified CT severity index by incorporating lymphocyte-to-monocyte ratio for early stratification in acute pancreatitis: a single-center validation study

Background Acute pancreatitis is a common digestive system emergency with heterogeneous clinical courses, and early accurate stratification is crucial for guiding treatment, improving prognosis, and reducing mortality. Existing scoring systems such as the Modified CT Severity Index (MCTSI) primarily rely on imaging features, but alone may not fully reflect inflammatory status, while inflammatory markers like the Lymphocyte-to-Monocyte Ratio (LMR) show potential in predicting disease severity; however, studies combining both are insufficient. Objective To investigate the value of integrating LMR with MCTSI to construct a new scoring system (MCTSI-LMR) for early stratification in acute pancreatitis, optimizing clinical predictive efficacy. Methods A total of 216 patients with acute pancreatitis admitted to Hefei Third People’s Hospital from April 2022 to January 2025 were selected as the study subjects. All patients were divided into mild group (65 cases), moderately severe group (108 cases), and severe group (43 cases) according to the Atlanta classification criteria (2012 revision). All patients underwent abdominal CT scanning and complete blood count within 24 hours of admission to calculate MCTSI scores and LMR values. Using clinical outcomes as the gold standard, inter-group indicator differences and the diagnostic efficacy of the combined score were compared. Results Based on disease severity, the severe group had significantly lower LMR values than the mild and moderately severe groups ( t = 125.473, P < 0.001) and higher MCTSI scores ( t = 298.456, P < 0.001). The incidence of organ failure and mortality showed statistically significant differences between groups (χ 2 = 98.765, P < 0.001; χ 2 = 45.678, P < 0.001). Multivariate logistic regression analysis revealed that MCTSI score (Wald = 26.234, P < 0.001) and LMR (Wald = 41.156, P < 0.001) were independent predictors of severe acute pancreatitis. ROC curve analysis indicated that the MCTSI-LMR score had superior predictive performance compared to individual indicators ( Z = 3.456–5.678, P < 0.05). Conclusion The application of the MCTSI-LMR score in early stratification of acute pancreatitis can significantly enhance predictive efficacy, with notable differences combining imaging and inflammatory markers, providing a reliable tool for clinical early intervention and worthy of promotion and application.