LRINEC Score for Necrotizing Soft Tissue Infection

Why Use

The score may be helpful in providing an overall gestalt picture of a patient with a potential necrotizing soft tissue infection — but it cannot rule out this infection.

When to Use

Patient with a concerning history or physical exam (pain out of proportion to exam, rapidly progressive cellulitis, for example). Patient with an unconcerning story (can provide some reassurance if score is very low).

Formula

Pearls / Pitfalls

The LRINEC (Laboratory Risk Indicator for Necrotizing Fasciitis) score was developed to distinguish necrotizing fasciitis (nec fasc) from severe cellulitis or abscess. Retrospective observational study divided into a developmental cohort and a validation cohort. Included 145 patients with necrotizing fasciitis and 309 patients with severe cellulitis or abscesses admitted to Changi General Hospital. Developmental cohort consisted of 89 patients with nec fasc and 225 control patients. Necrotizing fasciitis defined as operative exploration finding: presence of grayish necrotic fascia, lack of resistance of normally adherent muscular fascia to blunt dissection, lack of bleeding of the fascia during dissection, and the presence of foul-smelling “dishwater” pus. From developmental cohort, authors derived scoring system of six criteria, each worth 0, 1, 2, or 4 points. Score was then “externally validated” on a separate cohort of 56 consecutive patients with nec fasc and 84 control patients with severe cellulitis or abscess seen at Singapore General Hospital during a similar time frame. Patients were classified into three groups: low (LRINEC score ≤5, <50% risk for nec fasc), moderate (LRINEC score 6-7, 50-75% risk for nec fasc), and high risk (LRINEC ≥8, >75% risk for nec fasc). Using LRINEC ≥6 as a cut-off for nec fasc yielded PPV of 92% and NPV of 96%. ~90% of patients with nec fasc had LRINEC ≥6 while only 3.1-8.4% of control patients had score ≥6. Points to keep in mind: 10% of patients with nec fasc still had a LRINEC score <6. There have been no prospective trials validating the LRINEC score. Subsequent validation studies have not replicated the numbers shown in the original study.

Management

Prompt fluid resuscitation and antibiotic administration are crucial in the treatment of necrotizing fasciitis. Consider early surgical consultation in borderline cases.

Critical Actions

A LRINEC score ≥6 is a reasonable cut-off to rule in necrotizing fasciitis, but a LRINEC <6 does not rule out the diagnosis.

Advice

All patients with a high clinical suspicion for necrotizing fasciitis should receive immediate surgical consultation for potential operative debridement. Consider calculating a LRINEC score to distinguish patients with severe cellulitis/abscess vs necrotizing fasciitis.

More Information

Criteria Value Points CRP (mg/L) <150 0 ≥150 4 WBC per mm³ <15 0 15-25 1 >25 2 Hemoglobin (g/dL) >13.5 0 11-13.5 1 <11 2 Sodium ≥135 0 <135 2 Creatinine ≤ 1.6 mg/dL / 141 µmol/L 0 >1.6 mg/dL / 141 µmol/L 2 Glucose ≤180 mg/dL / 10 mmol/L 0 >180 mg/dL / 10 mmol/L 1