Laboratory Risk Indicator for Necrotizing Fasciitis score for early diagnosis of necrotizing fasciitis in Darwin

Abstract

Background: Soft tissue infections are a major health burden in the Top End of the Northern Territory of Australia. Necrotizing fasciitis (NF) is associated with mortality rates from 8 to 40%. Early recognition and aggressive surgical debridement are the cornerstones of successful treatment. The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score, developed by Wong et al., uses six routine biochemical variables to aid early diagnosis. We aim to assess the diagnostic efficacy of the LRINEC score in our population.

Methods: A retrospective review of patients with NF between 2005 and 2013 was conducted. A time matched cohort of abscesses/cellulitis was selected. Admission bloods were used to calculate the LRINEC score. An intraoperative finding of NF was used as the gold standard definition for comparison. The diagnostic accuracy of the LRINEC score was assessed.

Results: Ninety-eight patients with NF and 205 control patients were identified. The area under the receiver operator curve for the LRINEC score in detecting NF was 0.925 (0.890-0.959, P < 0.001). The sensitivity of the LRINEC ≥5 for NF was 76.3%, with a specificity of 93.1%. The positive and negative predictive values were 95.5 and 88.1%, respectively. The positive and negative likelihood ratios were 11 and 0.25.

Conclusion: The LRINEC score is a useful, robust, non-invasive and easily calculated scoring system that can be used as an adjunct to early diagnosis of NF. However, a high degree of clinical suspicion remains the most important factor in early diagnosis of NF.

Keywords: early diagnosis; haematologic tests; necrotizing fasciitis; sensitivity and specificity; soft tissue infections.