Prospective Validation and Comparison of Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) and Site Other Than Lower Limb, Immunosuppression, Age, Renal Impairment, and Inflammatory Markers (SIARI) Scoring Systems for Necrotizing Fasciitis

Abstract

Introduction: Necrotizing fasciitis (NF) is a rapidly progressing infection of the soft tissues associated with high morbidity and mortality and hence it is a surgical emergency. Early diagnosis and treatment are of paramount importance. LRINEC (Laboratory Risk Indicator for Necrotizing Fasciitis) and SIARI (Site other than lower limb, Immunosuppression, Age, Renal impairment, and Inflammatory markers) scoring systems have been established for early and accurate diagnosis of necrotizing fasciitis. This study compared the two scoring systems for diagnosing NF, predicting management, and elucidating the prognostic performance for re-operation and mortality.

Methods: This prospective study was conducted in PGIMER Chandigarh, India, between February 2020 and June 2021. The study was approved by the Institutional Review Board (No. INT/IEC/2020-90). The clinical presentation, laboratory parameters, and imaging were used to classify patients into NF or severe cellulitis groups. We also calculated the LRINEC and SIARI scores. Demographic variables and mortality were recorded. The area under the receiver operating characteristic was used to express the accuracy of both scores at a cut-off LRINEC and SIARI scores of ≥6 and ≥ 4, respectively.

Results: The study comprised 41 patients with NF and 11 with severe cellulitis. Informed written consent was taken from all the participants. At LRINEC score ≥6, the C-statistic for NF diagnosis was 0.839 (95% confidence interval [CI] 0.682-0.995, P 0.001), which was better than SIARI score at ≥ 4, C-statistic of 0.608 (95% CI 0.43-0.787, P 0.297). Both scores accurately predicted 30-day mortality. The LRINEC score showed a C-statistic of 0.912 (95% CI 0.798-1, P 0.001). Simultaneously, the SIARI score showed 70% sensitivity and 77% specificity, with a C-statistic of 0.805 (0.62-0.99, P = 0.017).

Conclusions: LRINEC score is an effective diagnostic tool for distinguishing necrotizing fasciitis from severe cellulitis. Additional research is required to establish the SIARI score's external validity.

Keywords: Laboratory risk indicator for necrotizing fasciitis; Necrotizing fasciitis; Severe cellulitis; Site other than lower limb, Immunosuppression, Age, Renal impairment, and Inflammatory markers.