Validation of the laboratory risk indicator for necrotizing fasciitis (LRINEC) score for early diagnosis of necrotizing fasciitis

Chun-I Liao^a, Yi-Kung Lee^{a, b}, Yung-Cheng Su^{a, b}, Chin-Hsiang Chuang^a, Chun-Hing Wong^a

^a Department of Emergency Medicine, Buddhist Dalin Tzu Chi General Hospital, Chiayi, Taiwan
^b School of Medicine, Tzu Chi University, Hualien, Taiwan

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Abstract
Objective

Necrotizing fasciitis is a surgical emergency. It has a poor outcome after late operative intervention but the clinical diagnosis is difficult. The laboratory risk indicator for necrotizing fasciitis (LRINEC) score was first introduced in 2004 and several clinicians have suggested it is useful for early recognition of necrotizing fasciitis but its validation still needs to be examined. We collected our hospital data from May 2003 to September 2010 to validate whether the LRINEC score can aid in early recognition of necrotizing fasciitis.

Materials and Methods

This is a validation cohort study. We reviewed all necrotizing fasciitis patients admitted from the emergency department at Buddhist Tzu Chi Dalin General Hospital in Taiwan from May 2003 to September 2010. All patients had pathological diagnoses. We used multiple imputations for missing patient data. We analyzed these data and examined whether the LRINEC score had a higher diagnostic value than the clinical diagnosis before admission. We also examined the LRINEC score in patients with severe cellulitis to determine its usefulness in excluding necrotizing fasciitis.

Results

A total of 233 patients with necrotizing fasciitis and 3155 with severe cellulitis were included in our study. A LRINEC score ≥6 had a sensitivity of 59.2% (CI 52.9–65.6%), specificity of 83.8% (CI 81.9–85.7%), likelihood ratio of 3.89, positive predictive ratio of 37.9% (95% CI 32.9–42.9%), and negative predictive ratio of 92.5% (95% CI 91.0–94.0%). The rate of clinical diagnosis of necrotizing fasciitis by emergency physicians before admission was 58.4% (95% CI 52.0–64.8%). Of the 97 patients with necrotizing fasciitis who were not clinically diagnosed before admission, 43.3% (95% CI 36.9–49.7%) had a LRINEC score <6.

Conclusion

The LRINEC score is an impressive diagnostic tool to distinguish necrotizing fasciitis from other severe soft tissue infections, but it is not useful for early recognition of necrotizing fasciitis.

Keywords
Laboratory risk indicator for necrotizing fasciitis (LRINEC); Necrotizing fasciitis; Necrotizing soft tissue infection