Sequential Organ Failure Assessment (Vincent 1996). Sepsis-3 operational definition.

What it is and when to use it

The SOFA (Sequential Organ Failure Assessment) score quantifies the severity of organ dysfunction in critically ill patients by assessing six systems: respiratory (PaO₂/FiO₂), coagulation (platelets), hepatic (bilirubin), cardiovascular (mean arterial pressure or vasopressor requirement), neurological (Glasgow Coma Scale) and renal (creatinine or urine output). Each system scores 0 to 4, for a total of 0 to 24. It is used to track the evolution of organ dysfunction in the ICU and is the central tool of the Sepsis-3 definition (2016), endorsed by SCCM/ESICM, which characterises sepsis as life-threatening organ dysfunction secondary to infection.

How to interpret it

The score is the sum of points across organs (0-4 per system, total 0-24); higher values indicate greater dysfunction and higher mortality. Within Sepsis-3, an acute rise of ≥2 points from baseline SOFA in a patient with infection defines sepsis and is associated with an in-hospital mortality of roughly 10% or higher. Higher initial and maximum scores, and especially a SOFA that increases over the first days of admission, predict a worse prognosis; a falling SOFA suggests response to treatment. There is no single universal dichotomous survival threshold: its value is primarily longitudinal and comparative.

Limitations and when not to use it

Validated in critically ill adult patients, mainly in ICU settings; adapted paediatric and neonatal versions exist (pSOFA, nSOFA) that must not be interchanged with the adult version. It requires laboratory and blood-gas data, so it is not suited to rapid bedside screening (qSOFA was used for that purpose, though it is now discouraged as a standalone screening tool). SOFA measures organ dysfunction and severity; it does not by itself diagnose infection or sepsis and does not replace clinical judgement. Components such as the Glasgow Coma Scale may be confounded by sedation and creatinine by pre-existing chronic kidney disease.

Frequently asked questions

What is the difference between SOFA and qSOFA?

SOFA is a full 0-24 score requiring laboratory data to quantify dysfunction across six organs, whereas qSOFA is a rapid 3-item bedside tool (respiratory rate, altered mentation, systolic blood pressure) intended for screening outside the ICU, now with a more limited role.

What does a 2-point increase in SOFA mean?

In a patient with suspected or confirmed infection, an acute rise of ≥2 points above baseline SOFA defines sepsis under the Sepsis-3 criteria and identifies a clinically significant mortality risk.

Can SOFA be used in children?

Not directly; the adult version was validated in critically ill adults. Age-specific adaptations exist for paediatric and neonatal populations (pSOFA and nSOFA) with their own thresholds.