Hong Life CalculatorsUnderstanding the SOFA score calculator — concept and principle
The Sequential Organ Failure Assessment (SOFA) score gives 0–4 points to each of six organ systems to describe how much organ dysfunction a critically ill patient has. It is recorded daily in intensive care and is the basis of the Sepsis-3 definition.
How it is calculated
SOFA (0–24) = respiration + coagulation + liver + cardiovascular + brain + kidney
- Respiration (PaO₂/FiO₂): ≥400 0, <400 1, <300 2, <200 with support 3, <100 with support 4.
- Platelets (×10³/µL): ≥150 0, <150 1, <100 2, <50 3, <20 4.
- Bilirubin (mg/dL): <1.2 0, 1.2–1.9 1, 2.0–5.9 2, 6.0–11.9 3, ≥12 4.
- Cardiovascular: MAP ≥70 0, MAP <70 1, then 2–4 by vasopressor type and dose.
- GCS: 15 0, 13–14 1, 10–12 2, 6–9 3, <6 4.
- Kidney: creatinine <1.2 0, 1.2–1.9 1, 2.0–3.4 2, 3.5–4.9 or urine <500 mL/day 3, ≥5.0 or urine <200 mL/day 4.
The principle
Vincent and colleagues (1996) designed SOFA to describe organ dysfunction simply and repeatedly over time rather than to predict death on day one. Each organ is scored on a common 0–4 scale based on routine measurements, so changes in the total track whether a patient is improving or worsening. Rising scores are associated with higher mortality.
Worked example
Default inputs: PaO₂ 75, FiO₂ 40%, ventilated; platelets 120; bilirubin 1.5 mg/dL; MAP below 70; GCS 14; creatinine 1.4 mg/dL; urine 500 mL/day or more.
- P/F = 75 ÷ 0.40 = 188 → below 200 with support → 3.
- Platelets 120 → 1; bilirubin 1.5 → 1; MAP <70 → 1.
- GCS 14 → 1; creatinine 1.4 → 1.
- SOFA = 3 + 1 + 1 + 1 + 1 + 1 = 8.
| PaO₂ (mmHg) | SOFA score (0–24) |
|---|---|
| 18.8 | 9 |
| 37.5 | 9 |
| 56.2 | 8 |
| 75 | 8 |
| 93.8 | 7 |
| 112 | 7 |
| 150 | 6 |
How to read the result
Higher scores mean more organ dysfunction. A rise of 2 or more points from baseline with infection defines sepsis. The trend over days is often more informative than a single value.
Common mistakes
- Scoring respiration 3 or 4 without breathing support.
- Using GCS under sedation without noting the assumed value.
- Not using the worst value of the day.
Frequently asked questions
What SOFA score is high?
There is no single cut-off; higher scores and rising trends indicate worse organ function.
How is SOFA used in sepsis?
A rise of 2 or more points with infection defines sepsis under Sepsis-3.
Why use worst daily values?
To capture the peak of dysfunction each day consistently.
Sources: 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;22(7):707–710