Retrospective evaluation of laboratory‐based diagnostic tools for cervical necrotizing fasciitis

Abstract Objectives/Hypothesis: Cervical necrotizing fasciitis (CNF) is challenging to diagnose and associated with high morbidity and mortality. The objective of this study is to evaluate the utility of two laboratory‐based diagnostic tools for distinguishing necrotizing from non‐necrotizing infection when specifically applied to neck infection. Study Design: Retrospective review. Methods: We reviewed 17 consecutive cases of CNF and 70 cases of non‐necrotizing neck infection (cellulitis, phlegmon, abscess) occurring at our institution over a 10.75‐year period. Cervical necrotizing fasciitis was confirmed by operative report documentation. Patient demographics, presenting characteristics, and outcomes were recorded. Results: Use of white blood cell count and serum sodium levels to predict cervical necrotizing fasciitis had a sensitivity of 24% (95% confidence interval [CI], 0.078‐0.502), specificity of 81% (95% CI, 0.688‐0.889), positive predictive value of 23% (95% CI, 0.054‐0.401), and negative predictive value of 81% (95% CI, 0.769‐0.857). A Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score of ≥ 6 had a sensitivity of 56% (95% CI, 0.227‐0.847), specificity of 60% (95% CI, 0.274‐0.863), positive predictive value of 25% (95% CI, 0.072‐0.433), and negative predictive value of 85% (95% CI, 0.733‐0.962). Conclusions: Neither the LRINEC score nor the use of admission white blood cell count and sodium level were useful for distinguishing cervical necrotizing fasciitis from non‐necrotizing neck infection.