SOFA Score: Sequential Organ Failure Assessment (Sepsis-3)

Understanding the SOFA Score and Sepsis-3 Definitions

The Sequential Organ Failure Assessment (SOFA) is a clinical scoring system widely used in intensive care units (ICU) to objectively quantify the severity of organ dysfunction. Since the Sepsis-3 consensus in 2016, the SOFA score has replaced the SIRS criteria. Sepsis is now defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection.

The 6 Organ Systems Evaluated

The SOFA score assesses the function of six key organ systems, assigning each a score from 0 (normal) to 4 (severe failure):

• Respiratory: Based on the PaO₂/FiO₂ ratio. High scores require mechanical ventilation.
• Coagulation: Evaluated by platelet count.
• Liver: Quantified by serum bilirubin levels.
• Cardiovascular: Evaluated by Mean Arterial Pressure (MAP) and the need for vasopressors.
• Neurological: Measured by the Glasgow Coma Scale (GCS).
• Renal: Based on creatinine elevation or severe oliguria.

SOFA vs qSOFA (Quick SOFA)

The qSOFA uses 3 rapid clinical criteria (altered mental status, systolic BP ≤ 100 mmHg, respiratory rate ≥ 22/min) to identify high-risk infected patients outside the ICU. The full SOFA score is used to confirm and quantify organ failure.

Estimated Hospital Mortality

Initial SOFA Score	Mortality
0 - 1	~ 0.0 %
2 - 3	~ 6.4 %
4 - 5	~ 20.2 %
6 - 7	~ 21.5 %
8 - 9	~ 33.3 %
10 - 11	~ 50.0 %
12 - 14	~ 95.2 %
> 14	> 95.2 %

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References:

1. Singer M, Deutschman CS, Seymour CW, et al. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). JAMA. 2016. [JAMA Network]
2. Vincent JL, Moreno R, Takala J, et al. The SOFA (Sepsis-related Organ Failure Assessment) score to describe organ dysfunction/failure. Intensive Care Med. 1996. [PubMed]