{
  "abstract": "BackgroundThe Sequential Organ Failure Assessment (SOFA) score describes organ dysfunction in intensive care. SOFA-2, published in 2025, updates the 1996 score (SOFA-1). It is unknown whether the update changes mortality discrimination and calibration within patient subgroups.\n\nMethodsWe analyzed 85,228 first ICU stays per hospitalization (65,354 adults) in MIMIC-IV v3.1. We scored SOFA-1 (two prespecified conventions for intubated patients) and SOFA-2 from the same data over the same first 24 hours. The primary outcome was in-hospital mortality; ICU mortality was secondary. Using a paired patient-level bootstrap (5,000 replicates), we estimated AUROC overall and by sex, race and insurance; the paired change between scores; subgroup gaps in AUROC and the change in those gaps; and descriptive calibration. The protocol was committed before any analysis relating scores to mortality.\n\nResultsIn-hospital death occurred in 9,468 stays (11.1%). AUROC was 0.762 for SOFA-2, 0.743 for SOFA-1 as charted and 0.735 for SOFA-1 under the community convention; SOFA-2 minus SOFA-1 was +0.019 (+0.016 to +0.023) and +0.027 (+0.023 to +0.031). Swapping single domains showed that the respiratory domain accounted for the whole gain, about 74% of it through the SpO2/FiO2 fallback. Subgroup gaps changed against SOFA-1 as charted (male-female +0.021; White-Black +0.025), driven by the brain-domain rule, but not against the community convention. The White-Black change was not seen in patients under 65, and neither change was consistent across ICU types. Calibration differences between groups were large but changed little between scores (|{Delta} log O/E| [≤] 0.045). Insurance-group differences largely disappeared in patients under 65, whereas race-group differences did not.\n\nConclusionsSOFA-2 modestly improved overall discrimination for in-hospital mortality, mainly through its respiratory domain. Changes in subgroup performance gaps were small. They depended on how SOFA-1 handles intubated patients, partly reflected age, and were not consistent across ICU types. These are descriptive associations in a single database; we draw no causal or fairness conclusions.",
  "abstract_shown": true,
  "affiliations": [
    "Harvard University"
  ],
  "article_type": "PUBLISHAHEADOFPRINT",
  "arxiv": null,
  "author_total": 5,
  "authors": [
    {
      "name": "K. Balakrishna"
    },
    {
      "affs": [
        0
      ],
      "name": "V. Bhatt"
    },
    {
      "name": "A. Hammond"
    },
    {
      "name": "R. Pirracchio"
    },
    {
      "name": "A. H. Zai"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/83d5rs61hnvv8.bib",
  "cited_by": 0,
  "doi": "10.64898/2026.10.23.26366238",
  "fulltext_url": "https://www.medrxiv.org/content/10.64898/2026.10.23.26366238v1.full",
  "id": "83d5rs61hnvv8",
  "issns": [],
  "landing_url": "https://www.medrxiv.org/content/10.64898/2026.10.23.26366238v1",
  "language": null,
  "licence": "CC-BY-NC-ND",
  "licence_label": "CC BY-NC-ND",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by-nc-nd/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "medrxiv",
      "intensive care and critical care medicine"
    ],
    [
      "openalex",
      "2713|Sepsis Diagnosis and Treatment"
    ]
  ],
  "openalex": "W7223674524",
  "pdf_url": "https://www.medrxiv.org/content/10.64898/2026.10.23.26366238v1.full.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-23",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/83d5rs61hnvv8.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:21:47Z",
      "native_id": "10.64898/2026.10.23.26366238",
      "source": "medrxiv",
      "url": "https://www.medrxiv.org/content/10.64898/2026.10.23.26366238v1"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "openalex:2713|Sepsis Diagnosis and Treatment",
      "subfield": "epidemiology-public-health"
    }
  ],
  "title": "Does Replacing SOFA-1 with SOFA-2 Change Mortality Discrimination and Calibration Across Patient Subgroups? A Paired Analysis in MIMIC-IV",
  "title_text": "Does Replacing SOFA-1 with SOFA-2 Change Mortality Discrimination and Calibration Across Patient Subgroups? A Paired Analysis in MIMIC-IV",
  "type": "preprint",
  "updated_at": "2026-10-30T12:21:47Z",
  "url": "https://research.draconitic.com/paper/83d5rs61hnvv8",
  "venue": "medRxiv",
  "versions": []
}