Comparison of Pan-Immune Inflammation Value (PIIV) and C-Reactive Protein (CRP) as Severity Markers in Acute Left-Colonic Diverticulitis Based on WSES Classification: A Retrospective Cohort Study

This study compared the diagnostic and prognostic performance of the Pan-Immune Inflammation Value (PIIV) and C-reactive protein (CRP) in assessing disease severity and predicting clinical outcomes in patients with acute left colonic diverticulitis (ALCD) classified according to the World Society for Emergency Surgery (WSES) guidelines. A retrospective cohort study was conducted including 281 patients diagnosed with ALCD at a single center between January 2017 and June 2025. Patients were stratified according to WSES classification as uncomplicated (Stage 0), moderately severe (Stage 1a/1b), and severely complicated (Stage 2a–4). Demographic data, clinical characteristics, and laboratory parameters (CRP and PIIV) obtained at admission and at 48 h were analyzed. Statistical analyses included ROC curve analysis, ANOVA, Kruskal–Wallis testing, and multivariable logistic regression. A p-value < 0.05 was considered statistically significant. Among the patients, 146 (51.9%) had uncomplicated disease, 87 (30.9%) had moderately severe disease, and 48 (17.2%) had severe complicated disease. Neither biomarker reliably differentiated uncomplicated from moderately severe cases; however, PIIV showed superior discriminatory ability (AUC 0.72 vs. 0.54, p = 0.005). PIIV also outperformed CRP in identifying severe complicated disease (AUC 0.85 vs. 0.76, p = 0.021). The optimal cutoff values for severe disease were 1429.00 for PIIV (sensitivity 78.4%, specificity 81.1%) and 123.80 mg/L for CRP (sensitivity 70.3%, specificity 73.1%). PIIV was an independent predictor of invasive interventions ( OR 1.04 per 100-unit increase , 95% CI 1.02–1.07 , p = 0.001). PIIV is superior to CRP for evaluating disease severity and predicting adverse outcomes in ALCD and may improve early risk stratification and patient management.