LRINEC Score for Necrotizing Soft Tissue Infection Calculator

How does this LRINEC score for necrotizing soft tissue infection calculator work?

This is a health tool that aims to evaluate whether a patient is suffering from necrotizing fasciitis (nec fasc) rather than from severe cellulitis or abscess. It is based on the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) observational study and the consequent validation reports.

The LRINEC score for necrotizing soft tissue infection calculator comprises of six criteria, main laboratory test results, each with variables that are awarded a number of points between 0 and 4 as follows:

■ C Reactive Protein – serologic measure of the acute phase reactant, liver protein released in the blood flow after tissue injury, sign of infection and/ or inflammation;

■ White Blood Cell count – main sign of infection, any rise in WBC;

■ Hemoglobin;

■ Serum Sodium – evaluating electrolyte, acid-base and renal function during infection in this case;

■ Creatinine – showing the kidney function;

■ Glucose – in diabetics strict glycemic control should be maintained and even supplemented with IV insulin if necessary.

The score can be applied in patients for whom the clinician is concerned after the physical exam but also in patients where there is an assumed minor risk of nec fasc but the score could be used in discriminating between conditions.

One of the criticisms received by the model concerns that it doesn’t have the relevant sensitivity as to rule out infection, therefore most patients where the score result continues to raise a suspicion should have a surgical consultation in order to progress further with operative debridement if deemed necessary.

LRINEC interpretation

The LRINEC score was mainly developed as a mean to distinguish NF from other  non-necrotizing soft tissue infections based on clinical determinations that are common for most diagnoses of soft tissue conditions. Therefore it allows a risk stratification of patients with cellulitis signs in determining how probable it is for them to develop a severe condition and NF. The score does have the specificity to put a prospective diagnosis early in the course of the disease.

The total score after the assessment is completed is between 0 and 13. Scores of above 6 make the cut off rule. The patient results are divided in three categories:

■ Low risk – scores between 0 and 5 – with less than 50% risk of diagnosis of nec fasc. The patient should still be monitored and administered IV antibiotics.

■ Intermediate risk – scores of 6 and 7 – with a risk of diagnosis between 50 and 75%. Urgent MRI evaluation and frozen biopsy are required, then if positive followed by operative debridement. If negative, the patient should still undergo IV antibiotic medication and be monitored for changes.

■ High risk – scores of 8 and above – with a risk of PPV of 92% and NPV of 96%. MRI and biopsy evaluations are required but most likely the patient will need operative debridement.

Necrotizing fasciitis guidelines

NF, also known as flesh-eating disease, is one of the rapidly progressive infections of thefascia and subcutaneous tissue and can be either limb or life threatening if left undiagnosed and untreated. Early recognition is essential in having a good and risk free prognostic and in avoiding later complications.

Necrotizing fasciitis in operative findings is defined as the presence of one or more of the following:

■ grayish necrotic fascia;

■ lack of resistance of normally adherent muscular fascia to blunt dissection;

■ lack of bleeding of the fascia during dissection;

■ foul-smelling “dishwater” pus.

Some of the risk factors include diabetes mellitus, obesity, immunosuppression, substance abuse, trauma, surgery or chronic systemic disease. Amongst the bacterial causes there are the Group A streptococcus (Streptococcus pyogenes), Staphylococcus aureus or the Clostridium perfringens.

Necrotizing fasciitis treatment comprises mainly of sudden operative debridement, fluid resuscitation and IV antibiotic administration such as vancomycin and clindamycin and in some cases post surgical debridement and skin grafting.

References

1) Wong CH, Khin LW, Heng KS, Tan KC, Low CO. (2004) The LRINEC (Laboratory Risk Indicator for Necrotizing Fasciitis) score: a tool for distinguishing necrotizing fasciitis from other soft tissue infections. Crit Care Med; 32(7):1535-41.

2) Borschitz T, Schlicht S, Siegel E, Hanke E, von Stebut E. (2015) Improvement of a Clinical Score for Necrotizing Fasciitis: 'Pain Out of Proportion' and High CRP Levels Aid the Diagnosis. PLoS One; 10(7):e0132775.

3) Bozkurt O, Sen V, Demir O, Esen A. (2015) Evaluation of the utility of different scoring systems (FGSI, LRINEC and NLR) in the management of Fournier's gangrene. Int Urol Nephrol; 47(2):243-8.