Interleukin-6 for Early Discrimination Between Type I and Type II Necrotizing Fasciitis

Objective: We evaluated the early diagnostic value of interleukin-6 (IL-6) for type I and type II necrotizing fasciitis (NF). Methods: A retrospective analysis was conducted of patients with NF between September 2020 and December 2024. They were divided into type I and type II NF. General clinical data, cytokines, and inflammatory markers were compared between the two groups. Threshold cytokine concentrations predictive of type I and type II NF were determined using receiver-operating characteristic (ROC) curve analysis. Results: A total of 106 patients with NF were included in the study, 74 cases (69.8%) were type I NF, whereas 32 cases (30.2%) were type II. The most commonly identified pathogens associated with type II NF included staphylococcus (n = 16). Cytokine and inflammatory marker analysis of type I NF patients compared with type II NF demonstrated elevated plasma IL-6 concentration in type II NF, and IL-6 remained correlated with type II NF on logistic regression after confounder adjustment (p < 0.05). In addition, ROC analysis revealed plasma IL-6 as a strong type II NF predictor. The area under the curve of plasma IL-6 was 0.94 (95% confidence interval: 0.86-1.00, p < 0.05). At the optimal cutoff value of 75.10 pg/mL, the sensitivity and specificity reached 91% and 100%, respectively. Conclusions: Interleukin-6 can be a supplementary diagnostic marker for early differentiation between type I and type II NF. Clinical Trial Registration: KY2022-R142.