Comparative prognostic performance of SOFA-1 and SOFA-2 in patients with sepsis at ICU admission

Lifang Lin; Zhifei Fu; Hongxia Sun; Yongye Wang; Sheng Zhang; Songjie Bai; Xuehuan Wen

doi:10.1016/j.clinme.2026.100601

Comparative prognostic performance of SOFA-1 and SOFA-2 in patients with sepsis at ICU admission

Clin Med (Lond). 2026 May 24;26(4):100601. doi: 10.1016/j.clinme.2026.100601. Online ahead of print.

Authors

Lifang Lin¹, Zhifei Fu², Hongxia Sun³, Yongye Wang⁴, Sheng Zhang⁵, Songjie Bai⁶, Xuehuan Wen⁷

Affiliations

¹ Department of Surgery, Cangnan Hospital of Traditional Chinese Medicine, Wenzhou, Zhejiang, China.
² Department of Emergency, Zhejiang Medical & Health Group Hangzhou Hospital of Hangzhou Medical College, Hangzhou, Zhejiang, China.
³ Wenzhou Medical University, Wenzhou, Zhejiang, China.
⁴ Department of Traditional Chinese Medicine, The People's Hospital of Cangnan Zhejiang, Wenzhou Medical University, Wenzhou, Zhejiang, China.
⁵ Department of Critical Care Medicine, Taizhou Hospital of Zhejiang Province, affiliated to Wenzhou Medical University, Taizhou, China. Electronic address: zhangs@enzemed.com.
⁶ Department of Cardiovascular Surgery ICU, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, Jiangxi, China. Electronic address: songjie.bai@ncu.edu.cn.
⁷ Department of Oncology, The People's Hospital of Cangnan Zhejiang, Wenzhou Medical University, Wenzhou, Zhejiang, China. Electronic address: wxh2024@zuaa.zju.edu.cn.

Abstract

Study objective: SOFA-1 underpins Sepsis-3 definitions but may no longer optimally reflect contemporary ICU practice; SOFA-2 was recently developed from large multinational datasets, yet its prognostic performance in septic populations remains unknown. We aimed to compare the prognostic performance of SOFA-1 and SOFA-2 in ICU patients with sepsis.

Design: Retrospective cohort study.

Setting and participants: This study was conducted using the MIMIC-IV database. A total of 30,667 adult patients (≥18 years) with first ICU admissions meeting Sepsis-3 criteria were included.

Main outcome measures: ICU mortality and in-hospital mortality. We compared discrimination (AUC), calibration, net reclassification improvement (NRI), integrated discrimination improvement (IDI), decision curve analysis and time-dependent survival.

Results: Among 30,667 patients, 87.0% met both SOFA-1 and SOFA-2 criteria, 12.0% met only SOFA-2 criteria, and 1.0% met only SOFA-1 criteria. SOFA-2 total scores were systematically higher than SOFA-1, driven primarily by updated renal, cardiovascular and brain scoring criteria. SOFA-2 demonstrated modestly but consistently better discrimination for ICU mortality (AUC 0.779 vs. 0.755; P < 0.001) and hospital mortality (AUC 0.745 vs. 0.725; P < 0.001), with significant reclassification improvement for ICU mortality (NRI 0.143; IDI 0.020). In multivariable Cox models, SOFA-2 achieved higher AUCs for 7-day (0.790 vs. 0.771), 28-day (0.709 vs. 0.697) and 90-day mortality (0.682 vs. 0.671; all P < 0.001), with consistent advantages across all prespecified subgroups.

Conclusions: SOFA-2 provides modestly but consistently better prognostic performance than SOFA-1 in septic ICU patients. Whether this incremental gain justifies the added scoring complexity warrants prospective evaluation.

Keywords: Mortality prediction; Risk stratification; SOFA-1; SOFA-2; Sepsis.