What Is the SOFA Score?

The Sequential Organ Failure Assessment (SOFA) score was developed by Vincent et al. in 1996 to describe and quantify the degree of organ dysfunction in critically ill patients. Since the landmark Sepsis-3 consensus in 2016, SOFA has become the official diagnostic criterion for sepsis: a SOFA score increase of ≥ 2 points from baseline in a patient with suspected infection defines sepsis.

Understanding how to calculate SOFA accurately is one of the most important clinical skills for any intensivist, emergency physician, or hospitalist.

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The 6 Organ Systems — Step by Step

SOFA evaluates six organ systems, each scored 0–4. The maximum total score is 24.

Step 1 — Respiratory System (PaO₂/FiO₂ Ratio)

The respiratory component uses the P/F ratio (PaO₂ in mmHg divided by FiO₂ as a decimal):

Clinical tip: If the patient is not intubated and SpO₂ is available, use the SpO₂/FiO₂ ratio as a surrogate (SpO₂/FiO₂ < 315 ≈ P/F < 300).

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Step 2 — Coagulation (Platelet Count)

Clinical tip: Thrombocytopenia in sepsis reflects DIC, bone marrow suppression, or platelet consumption. A rapid drop from 200 to 80 in 24 hours is clinically significant even if the absolute value is not critically low.

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Step 3 — Liver (Bilirubin)

Clinical tip: Hepatic dysfunction in sepsis is often underappreciated. Rising bilirubin in the first 48–72 hours of ICU admission is an independent predictor of mortality.

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Step 4 — Cardiovascular (Vasopressor Requirement)

This is the most complex component:

Clinical tip: Vasopressor doses must be maintained for at least 1 hour to score. Transient hypotension during procedures does not count.

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Step 5 — Neurological (Glasgow Coma Scale)

Clinical tip: In sedated patients, use the pre-sedation GCS or document that the neurological score cannot be assessed. Do not score a sedated patient as GCS 3 — this artificially inflates the SOFA score.

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Step 6 — Renal (Creatinine and Urine Output)

Clinical tip: Use the worst value (highest creatinine or lowest UOP) over the assessment period. In patients on CRRT, assign a renal score of 4.

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Try the Live SOFA Calculator

Use the embedded calculator below to calculate SOFA score for your patient in real time:

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Interpreting Your SOFA Score

Single-Point Interpretation

The Sepsis-3 Diagnostic Threshold

Sepsis = Suspected infection + SOFA increase ≥ 2 from baseline

The baseline SOFA is assumed to be 0 in patients without known organ dysfunction. In patients with pre-existing organ failure (e.g., CKD, cirrhosis), use the known baseline.

Septic shock = Sepsis + vasopressor requirement (MAP ≥ 65 mmHg) + lactate > 2 mmol/L despite adequate resuscitation

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Serial SOFA: The Most Powerful Use

A single SOFA score is informative, but serial SOFA is where the real clinical value lies:

• •Increasing SOFA in the first 48 hours → 37–50% ICU mortality regardless of initial score
• •Decreasing SOFA → strong predictor of recovery and treatment response
• •Delta SOFA (change from admission to 48h) is a better predictor of mortality than the absolute score

Practical protocol: Calculate SOFA at admission, 24 hours, and 48 hours. A decrease of ≥ 2 points at 48 hours is a meaningful positive response to treatment.

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qSOFA: The Bedside Screening Tool

For patients outside the ICU where full SOFA calculation is impractical, qSOFA (quick SOFA) provides rapid screening:

• •Respiratory rate ≥ 22 breaths/min (+1)
• •Altered consciousness — GCS < 15 (+1)
• •Systolic BP ≤ 100 mmHg (+1)

qSOFA ≥ 2 = high risk for sepsis-related organ dysfunction → escalate care, calculate full SOFA, consider ICU transfer. Important: qSOFA is a screening tool, not a diagnostic criterion. A negative qSOFA does not rule out sepsis.

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Common SOFA Calculation Errors

1. Using average values instead of worst values

SOFA uses the worst (most abnormal) value in the assessment period, not the mean.

2. Scoring sedated patients on GCS

Document pre-sedation GCS or note that neurological assessment is not possible. Do not score GCS 3 for a pharmacologically sedated patient.

3. Ignoring baseline organ dysfunction

In patients with CKD (baseline creatinine 2.5 mg/dL), a creatinine of 2.8 mg/dL represents minimal change — not a SOFA score of 2. Always compare to the patient's baseline.

4. Not reassessing serially

A single SOFA score at admission is far less informative than the trend. Build serial SOFA assessment into your daily ICU workflow.

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SOFA vs. APACHE II: When to Use Each

Use SOFA for daily organ dysfunction monitoring and sepsis diagnosis. Use APACHE II for admission mortality prediction and ICU benchmarking.

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Key References

• •Vincent JL et al. The SOFA (Sepsis-related Organ Failure Assessment) score to describe organ dysfunction/failure. *Intensive Care Med.* 1996;22(7):707–710.
• •Singer M et al. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). *JAMA.* 2016;315(8):801–810.
• •Ferreira FL et al. Serial evaluation of the SOFA score to predict outcome in critically ill patients. *JAMA.* 2001;286(14):1754–1758.