The new SOFA for sepsis identification and mortality prediction: a multicenter cohort study

The Sequential Organ Failure Assessment (SOFA) score is central to Sepsis-3 criteria. SOFA-2 updates thresholds and incorporates contemporary organ support practices, but its impact on sepsis identification and outcome prediction remains uncertain. This study aimed to compare the diagnostic yield and prognostic performance of SOFA-2 versus SOFA-1 for sepsis identification in critically ill adults.

We conducted a retrospective multicenter cohort study of 11,669 ICU admissions from three tertiary hospitals in China (January 2022-October 2025) and externally validated findings in 29,811 ICU patients from MIMIC-IV. Sepsis was defined by Sepsis-3 using either SOFA-1 or SOFA-2. We evaluated diagnostic agreement, organ dysfunction profiles, and discrimination for ICU mortality.

SOFA-2 identified a significantly larger sepsis population than SOFA-1 (49.0% vs. 45.5%, P < 0.001), while maintaining substantial diagnostic agreement with SOFA-1 ( $k$ =0.891-0.908). Compared with SOFA-1, SOFA-2 assigned higher total scores in the mid-to-high range and captured more organ dysfunction. Despite these reclassifications, ICU and hospital length of stay and mortality did not differ significantly between sepsis-SOFA-1 and sepsis-SOFA-2 groups (all P > 0.05). SOFA-2 showed slightly but consistently higher discrimination for ICU mortality than SOFA-1 (internal AUC 0.720 vs. 0.703; external AUC 0.735 vs. 0.722) and clearer mortality gradients in moderate-to-severe dysfunction categories (P < 0.001).

The updated SOFA-2 score may identify a moderately larger sepsis population with more advanced organ dysfunction and may provide modestly improved mortality risk stratification compared with SOFA-1, while maintaining substantial diagnostic agreement. These findings suggest that SOFA-2 could be considered for clinical use in ICU sepsis assessment, and the Sepsis-3 SOFA ≥ 2 threshold may not require recalibration when using SOFA-2.