Clinical question / background:
- The goal of this study was to develop a diagnostic scoring system to distinguish necrotizing fasciitis from other soft tissue infections based on common laboratory evaluation.
Design:
- Retrospective observational study. Chart review of all patients diagnosed with necrotizing fasciitis (NF). Chart review of patients with cellulitis used as control.
- Initially developed rule with developmental cohort (n=314) and then validated with validation cohort (n=147).
- Inclusion criteria:
- Patients diagnosed with NF by chart review
- Control group of “severe soft tissue infections” identified by chart review of patients with documentation of soft tissue infection needing parenteral antibiotics for >48 hrs or abscess needing surgical debridement.
- Exclusion criteria:
- Minor soft tissue infection: length of stay less than 48 hours, oral antibiotics.
Outcome:
- Diagnosis of necrotizing fasciitis with scoring system as below (Based on developmental cohort)
- LRINEC scoring system:
- CRP (mg/L) ≥150: 4 points
- WBC count (×103/mm3)
- <15: 0 points
- 15–25: 1 point
- >25: 2 points
- Hemoglobin (g/dL)
- >13.5: 0 points
- 11–13.5: 1 point
- <11: 2 points
- Sodium (mmol/L) <135: 2 points
- Creatinine (umol/L) >141: 2 points
- Glucose (mmol/L) >10: 1 point
- Grouping by scoring
- Low Risk: score 5
- Moderate Risk: score 6-7
- High Risk: score >8
Results:
- LRINEC score >8 is strongly predictive of necrotizing fasciitis PPV 93%
- 89% of patients diagnosed with NF LRINEC score >6
- There were diagnoses of NF with LRINEC score of 0
Take-home:
- LRINEC score can raise suspicion of necrotizing fasciitis, however is not a “rule out”
- Does not replace clinical judgement
Weaknesses / Critiques
- Not prospectively validated.
