SOFA Criteria: Components and Scoring System
The Sequential Organ Failure Assessment (SOFA) score evaluates dysfunction across six organ systems—respiratory, coagulation, liver, cardiovascular, renal, and neurologic—with each system scored from 0 (normal) to 4 (most severe dysfunction), allowing serial assessment of critically ill patients over time.
The Six Organ Systems and Their Scoring
The SOFA score assesses the following organ systems 1, 2:
1. Respiratory System (PaO2/FiO2 ratio)
- 0 points: >400 mmHg
- 1 point: ≤400 mmHg
- 2 points: ≤300 mmHg
- 3 points: ≤200 mmHg
- 4 points: ≤100 mmHg
2. Coagulation/Hemostasis (Platelets)
- 0 points: ≥150,000/mm³
- 1 point: <150,000/mm³
- 2 points: <100,000/mm³
- 3 points: <50,000/mm³
- 4 points: <20,000/mm³ (or INR ≥2.5 in CLIF-SOFA) 2
3. Liver (Bilirubin)
- 0 points: <1.2 mg/dL
- 1 point: 1.2-1.9 mg/dL
- 2 points: 2.0-5.9 mg/dL
- 3 points: 6.0-11.9 mg/dL
- 4 points: ≥12.0 mg/dL
4. Cardiovascular System (Mean Arterial Pressure and Vasopressors)
- 0 points: MAP ≥70 mmHg
- 1 point: MAP <70 mmHg
- 2 points: Dopamine ≤5 μg/kg/min OR dobutamine (any dose) OR epinephrine ≤0.1 μg/kg/min OR norepinephrine (any dose)
- 3 points: Dopamine >5 μg/kg/min OR epinephrine >0.1 μg/kg/min OR norepinephrine ≤0.1 μg/kg/min
- 4 points: Dopamine >15 μg/kg/min OR epinephrine >0.1 μg/kg/min OR norepinephrine >0.1 μg/kg/min 2
5. Renal/Kidney (Creatinine)
- 0 points: <1.2 mg/dL
- 1 point: 1.2-1.9 mg/dL
- 2 points: 2.0-3.4 mg/dL
- 3 points: 3.5-4.9 mg/dL
- 4 points: ≥5.0 mg/dL (or urine output <500 mL/day)
6. Neurologic/Brain (Glasgow Coma Scale)
- 0 points: GCS 15
- 1 point: GCS 13-14
- 2 points: GCS 10-12
- 3 points: GCS 6-9
- 4 points: GCS <6
Key Clinical Applications and Limitations
SOFA was designed for sequential assessment of organ dysfunction in ICU patients with sepsis, not as a one-time prognostic tool 1, 3. The score allows tracking of disease evolution over the entire ICU stay through repeated measurements 1.
Important Caveats:
- Organ failure is typically defined as a subscore ≥3 points in any single organ system 4, 5
- SOFA does not incorporate age or chronic comorbidities, which are important mortality predictors 3
- The score was not intended to guide individual treatment decisions or indicate success/failure of interventions 3
- Total SOFA scores can be misleading—two patients with identical total scores may have vastly different organ dysfunction patterns and mortality risks 4, 5
Performance Characteristics:
When used for mortality prediction in complicated intra-abdominal infections, SOFA demonstrated good discriminative power with a pooled AUC of 0.75 3. However, APACHE II outperformed SOFA (AUC 0.81) for this specific application 3.
Modified Versions:
The CLIF-SOFA score adapts the original for cirrhotic patients, with special attention to renal and cerebral dysfunction, as even mild dysfunction in these organs significantly impacts mortality in this population 2.
A recently developed SOFA-2 score (2024-2025) updates thresholds and incorporates contemporary organ support practices, showing modestly improved discrimination (AUC 0.79 vs 0.77 for SOFA-1) 6, 7, 8, 9.
Practical Scoring Rules:
- Calculate the maximum score within the first 24 hours of ICU admission for initial assessment 5
- Serial measurements (daily for first 3-7 days) provide prognostic value—increasing scores predict mortality while decreasing scores suggest survival 10
- Always report individual organ subscores in research and clinical documentation, not just the total score 4