Diagnostic and prognostic utility of SIRI and CAR in necrotizing fasciitis: a retrospective cohort study on disease severity and clinical outcomes

Abstract Background Necrotizing fasciitis (NF), a fulminant soft tissue infection requiring urgent surgical intervention, presents substantial diagnostic challenges due to its non-specific clinical manifestations during initial stages. This study investigates the prognostic value of two novel inflammatory biomarkers—the systemic inflammatory response index (SIRI) and C-reactive protein-to-albumin ratio (CAR)—in predicting disease progression and clinical outcomes in NF patients. Methods This retrospective cohort study analyzed clinical data from 192 patients with confirmed soft tissue infections, comprising 50 necrotizing fasciitis (NF) cases and 142 non-NF presentations. Comparative analysis of SIRI, CAR, and key inflammatory markers was conducted between NF and non-NF cohorts during the perioperative 24-hour period. NF patients underwent severity stratification using Sequential Organ Failure Assessment (SOFA) criteria, categorized as severe (SOFA ≥ 2) or mild (SOFA < 2) subgroups. Univariable and multivariable logistic regression analyses were performed to identify independent risk factors associated with disease severity, and the predictive capacity of these factors was evaluated using receiver operating characteristic (ROC) curve analysis. Results The two groups exhibited comparable baseline characteristics and comorbidities, with no statistically significant differences detected (all P > 0.05). Among the 50 NF cases and 142 non-NF cases, the NF group showed significant elevations in inflammatory parameters, coagulation profiles, and metabolic/renal biomarkers compared with non-NF controls. Multivariable regression analysis established CAR, SIRI, blood glucose (GLU), and creatinine (Cr) as independent NF risk factors, showing area under the curve (AUC) values of 0.86, 0.78, 0.68, and 0.65 respectively. In NF severity assessments, CAR and SIRI emerged as independent predictors. ROC curve validation confirmed CAR (AUC = 0.70) and SIRI (AUC = 0.76) as robust severity stratification biomarkers in NF progression assessment. Conclusions SIRI and CAR serve as independent risk factors for the development and progression of necrotizing fasciitis, offering novel biomarkers for early diagnosis and prognostic evaluation. These findings could enhance clinical decision-making and optimize patient outcomes.