Diagnostic Accuracy of the LRINEC Score for Necrotizing Fasciitis Using Histopathology as the Gold Standard

Abstract

Background: Necrotizing fasciitis (NF) is a rapidly progressive, potentially life-threatening soft-tissue infection in which early diagnosis and surgical intervention are crucial. The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score uses routinely available laboratory parameters to assist in early diagnosis. This study evaluated the diagnostic performance of a LRINEC score ≥6 using histopathology as the reference standard

Objective: To determine the diagnostic accuracy and area under the receiver operating characteristic curve (AUROC) of a LRINEC score ≥6 for diagnosing NF.

Methods: A cross-sectional study was conducted from 20 May 2026 till 20 August 2026 at the Department of Surgery, Nishtar Hospital, Multan. Consecutive patients aged 18–60 years with clinically suspected NF and symptom duration ≤48 hours were enrolled. Blood samples were obtained before antibiotics and fluid resuscitation. White blood cell count, hemoglobin, serum sodium, glucose, creatinine, and C-reactive protein were measured, and the LRINEC score was calculated. All patients underwent surgical debridement, with tissue specimens submitted for histopathological examination. Diagnostic performance was assessed using sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), diagnostic accuracy, and AUROC.

Results: Among 128 patients, 94 (73.4%) had histopathologically confirmed NF. The mean age was 54.97 ± 2.65 years; 88 (68.8%) were male and 73 (57.0%) had diabetes mellitus. The mean LRINEC score was 7.23 ± 2.80. At a cutoff of ≥6, 85 true-positive, 31 true-negative, 9 false-negative, and 3 false-positive results were observed. Sensitivity was 90.4%, specificity 91.2%, PPV 96.6%, NPV 77.5%, and diagnostic accuracy 90.6%. The AUROC was 0.798 (95% CI: 0.720–0.876; p<0.001).

Conclusion: A LRINEC score ≥6 demonstrated good diagnostic performance for histopathologically confirmed NF. However, its negative predictive value was insufficient to reliably exclude NF. LRINEC should therefore complement, rather than replace, clinical assessment and urgent surgical evaluation.