External Validation of the Phoenix Sepsis Score in Children With Suspected Community-Acquired Sepsis

IMPORTANCE: The novel Phoenix Sepsis Score and sepsis criteria were derived and validated using a multicountry dataset and proposed as a new definition for sepsis in children. OBJECTIVE: To externally validate the Phoenix Sepsis Score and sepsis criteria in a cohort of children hospitalized with suspected community-acquired sepsis. DESIGN, SETTING, AND PARTICIPANTS: This diagnostic study used data from the multicenter, multicountry Sepsis Epidemiology in Australian and New Zealand Emergency Departments (SENTINEL) study, collected from 2021 to 2023 and including 90-day follow-up. Children admitted to the hospital through 11 emergency departments in Australia and New Zealand and treated with parenteral antibiotics with either (1) a provisional diagnosis of sepsis or (2) treatment for sepsis (intravenous fluid bolus to treat poor perfusion) were included. EXPOSURE: Development of organ dysfunction over the first 24 hours of hospitalization. MAIN OUTCOMES AND MEASURES: The main outcomes were (1) in-hospital mortality and (2) death or requirement for extracorporeal life support (ECLS) within 72 hours of hospitalization. RESULTS: A total of 6232 children were included in the analysis, with a median (IQR) age of 2.1 (0.3-7.1) years, 3386 (54.1%) male, in-hospital mortality of 60 (1.0%), and death or ECLS within 72 hours in 36 (0.6%). In this population, the worst Phoenix Sepsis Score calculated over the first 24 hours of hospitalization had an area under the precision recall curve of 0.17 (95% CI, 0.07-0.28) for predicting in-hospital mortality and 0.23 (95% CI, 0.11-0.36) for predicting death or ECLS within 72 hours. Overall, 306 children (4.9%) met the Phoenix sepsis criteria, of whom 33 (10.8%) died in the hospital (nearly half of the total number who died) and 28 (9.2%) died or required ECLS within 72 hours. The Phoenix sepsis criteria had a sensitivity of 55.0% (95% CI, 41.6%-67.9%) and positive predictive value (PPV) of 10.8% (95% CI, 7.6%-14.9%) for in-hospital mortality and sensitivity of 77.8% (95% CI, 60.8%-89.9%) and PPV of 9.2% (95% CI, 6.2%-13.0%) for death or ECLS within 72 hours. Coagulation data for the calculation of the Phoenix Sepsis Score were missing in more than 85% of children. CONCLUSIONS AND RELEVANCE: In this multicenter diagnostic study of children hospitalized with suspected sepsis, the Phoenix Sepsis Score and sepsis criteria had similar performance to the original derivation and validation cohorts. The small proportion of children meeting Phoenix sepsis criteria, missingness of data, timing of application, and lack of sensitivity for in-hospital mortality limit the clinical utility of the criteria.