Validation of the updated sequential organ failure assessment (SOFA)-2 score in emergency department septic shock.

OBJECTIVES: The original Sequential Organ Failure Assessment (SOFA-1) score is widely used to quantify organ dysfunction in critically ill patients, including those with septic shock. A recently updated, data-driven SOFA score (SOFA-2) revises component thresholds and incorporates contemporary organ support modalities. While SOFA-2 has been validated in intensive care unit populations, its performance in the emergency department (ED), particularly among patients with septic shock, is uncertain. We therefore sought to validate SOFA-2 in ED patients with septic shock. METHODS: In this observational study, we analyzed two prospective septic shock registries. Adult ED patients with septic shock were included. SOFA-1 and SOFA-2 scores were calculated using the worst physiologic and laboratory values recorded within the first 24 h in the ED. We compared score distributions and examined mortality across score ranges. Discrimination for in-hospital, 28-day, and 90-day mortality was evaluated using the area under the receiver operating characteristic curve (AUROC). Calibration for in-hospital mortality was assessed using the calibration curve and Brier scores. Reclassification performance was evaluated using continuous net reclassification improvement (NRI) and integrated discrimination improvement (IDI). RESULTS: The study included 2669 patients in Cohort A and 1443 patients in Cohort B. SOFA-1 and SOFA-2 score distributions differed significantly. Mortality generally increased with higher SOFA-1 and SOFA-2 scores across all outcomes. SOFA-2 demonstrated significantly higher AUROCs than SOFA-1 for in-hospital, 28-day, and 90-day mortality in both cohorts (Cohort A: 0.734 vs. 0.702, 0.719 vs. 0.694, and 0.680 vs. 0.658; Cohort B: 0.719 vs. 0.671, 0.737 vs. 0.689, and 0.711 vs. 0.666; all p < 0.001). SOFA-2 showed generally closer agreement between predicted and observed in-hospital mortality and lower Brier scores. Continuous NRI (0.276-0.635) and IDI (0.024-0.062) also favored SOFA-2 across all mortality outcomes (all p < 0.001). In adjusted analyses, each 1-point increase in SOFA-2 was independently associated with higher mortality. Sensitivity analyses and pooled analyses showed consistent findings. CONCLUSION: Among ED patients with septic shock, SOFA-2 showed modestly improved discrimination, closer agreement between predicted and observed in-hospital mortality with lower overall prediction error, and more favorable continuous reclassification metrics compared with SOFA-1. These findings support the external validation of SOFA-2 in this population and warrant further evaluation in diverse ED settings.