Beyond the LRINEC Score: A stratified diagnostic algorithm for subacute and atypical necrotizing fasciitis
A Schmitt1, C Barani1, M Pividori1
1Department of Plastic and Reconstructive Surgery, Saint-Joseph-Saint-Luc Hospital, 20, Quai Claude Bernard, 69007 Lyon, France.
Background:
While typical Necrotizing Soft Tissue Infections (NSTI) are clinically overt, atypical and subacute presentations pose a complex diagnostic challenge. These forms-characterized by subacute evolution, deceptive local signs, or atypical pathogens-often defy standard recognition patterns. The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score is frequently utilized for emergency risk stratification; however, its sensitivity remains contested in contemporary literature.
Methods:
We conducted a retrospective observational study (2007-2025) of 37 confirmed NSTI patients at a regional tertiary Plastic Surgery referral center. We analyzed admission physiology, microbiological profiles, and calculated retrospective LRINEC and SIARI (Site, Immuno, Age, Renal, Inflam) scores. To validate findings against potential data handling bias, a sensitivity analysis comparing zero-imputation versus complete case analysis was performed.
Results:
Despite high clinical severity (43.2% septic shock), the LRINEC score yielded a false negative rate of 18.9% (7/37 patients classified as "Low Risk"). These failures correlated with atypical profiles: head and neck localization, prior administration of non-steroidal anti-inflammatory drugs (NSAID), and subacute pathogens (Cutibacterium acnes, Actinomyces). Sensitivity analysis confirmed the statistical stability of these findings (P=0.66). Conversely, the SIARI score correctly reclassified all LRINEC false negative cases as high risk (Score ≥ 3).
Conclusion:
The LRINEC score exhibits insufficient negative predictive value to safely exclude atypical and subacute NSTIs, potentially causing hazardous delays in surgical intervention. We propose a stratified clinical algorithm designed to enhance surgical vigilance and reduce the risk of missed diagnosis.
Insights
The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score frequently misses atypical Necrotizing Soft Tissue Infections (NSTI), leading to diagnostic delays. The SIARI score offers improved risk stratification for these challenging cases.
Area of Science:
- Infectious Diseases
- Surgical Pathology
- Diagnostic Accuracy
Background:
- Atypical and subacute Necrotizing Soft Tissue Infections (NSTI) present diagnostic challenges due to subtle signs and unusual pathogens.
- The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score is commonly used but its sensitivity for NSTI is debated.
Purpose of the Study:
- To evaluate the diagnostic performance of the LRINEC score in a cohort of confirmed NSTI patients.
- To compare the LRINEC score with the SIARI score in identifying high-risk NSTI cases, particularly atypical presentations.
Main Methods:
- Retrospective observational study of 37 NSTI patients (2007-2025).
- Analysis of patient physiology, microbiology, and calculation of LRINEC and SIARI scores.
- Sensitivity analysis performed to ensure data integrity.
Main Results:
- LRINEC score had an 18.9% false negative rate, misclassifying 7/37 patients as low risk.
- LRINEC failures were associated with head/neck NSTI, NSAID use, and subacute pathogens (e.g., Cutibacterium acnes).
- SIARI score correctly identified all LRINEC false negatives as high risk.
Conclusions:
- LRINEC score has inadequate negative predictive value for atypical/subacute NSTI, risking delayed surgical treatment.
- A new stratified clinical algorithm is proposed to improve early detection and surgical intervention for NSTI.
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