Validation of necrotising infection clinical composite endpoint in a retrospective cohort of patients with necrotising soft tissue infections.

Introduction: Rapidly progressive necrotising soft tissue infections (NSTIs) are associated with high mortality and morbidity. Low incidence and disease heterogeneity contribute to low event rates and inadequately powered studies. The Necrotising Infections Clinical Composite Endpoint (NICCE) provides a binary outcome with which to assess interventions for NSTIs. Partly with a view towards studies of hyperbaric oxygen treatment in NSTIs we aimed to validate NICCE in a retrospective cohort of NSTI patients. Methods: Eligible patients were admitted between 2012 and 2021 to an adult major referral hospital in Victoria, Australia with surgically confirmed NSTI. The NICCE and its constituents were assessed in the whole cohort (n = 235). The cohort was divided into two groups using the modified sequential organ failure assessment (mSOFA) score, with an admission mSOFA score ≥ 3 defined as high acuity. Results: Baseline characteristics of the whole (n = 235), the high (n = 188) and the low acuity cohorts (n = 47) were similar. Survival rates were high (91.1%). Patients with an admission mSOFA ≥ 3 were less likely to meet NICCE criteria for 'success' compared to the lower acuity cohort (34.1% and 64.7% respectively). Meeting NICCE criteria was significantly associated with lower resource utilisation, measured by intensive care unit days, ventilator days, and hospital length of stay for all patients and for those with high acuity on presentation. Conclusions: The NICCE provides greater discriminative ability than mortality alone. It accurately selects patients at high risk of adverse outcomes, thereby enhancing feasibility of trials. Adaptation of NICCE to include patient-centred outcomes could strengthen its clinical relevance.