Prognostic Indices for Mortality Prediction in Fournier's Gangrene: A Comparative Study Introducing PCT-ALLY.

BACKGROUND: Fournier's gangrene is a life-threatening necrotizing fasciitis with mortality rates of 20%-50%. Early identification of high-risk patients is essential, yet practical prognostic tools derived from routine laboratory tests remain limited. AIM: To compare seven prognostic indices and develop a novel procalcitonin-based index (PCT-ALLY) for mortality prediction in patients with Fournier's gangrene. METHODS: In this single-center retrospective cohort, 220 surgically treated patients (January 2007-September 2025) were evaluated. Preoperative laboratory data were used to calculate neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio, hemoglobin-albumin-lymphocyte-platelet (HALP), prognostic nutritional index, systemic inflammation response index (SIRI), C-reactive protein-albumin-lymphocyte (CALLY), and the newly developed PCT-ALLY. The primary endpoint was 30-day or in-hospital mortality. Discrimination was assessed using receiver operating characteristic analysis with DeLong testing and multivariable logistic regression. RESULTS: Mortality occurred in 66 patients (30%). CALLY showed the highest area under the curve (0.935; 95% confidence interval [CI] 0.890-0.965), followed by PCT-ALLY (0.874; 95% CI 0.821-0.916). PCT-ALLY had the highest specificity (87.0%) and outperformed NLR ( P = 0.032) and SIRI ( P = 0.045). In multivariable analysis, CALLY (odds ratio [OR] 7.210; P < 0.001), HALP (OR 3.816; P < 0.001), and PCT-ALLY (OR 3.649; P < 0.001) were independent predictors of mortality. CONCLUSIONS: Immuno-nutritional indices, particularly CALLY and PCT-ALLY, provide strong, easily calculable, and cost-effective mortality prediction in Fournier's gangrene and may support early risk stratification. Prospective multicenter validation is warranted.