SOFA Score

The Sequential (Sepsis-related) Organ Failure Assessment (SOFA) score is a clinical scoring system used to track the status and severity of organ dysfunction in critically ill patients, particularly those with suspected or confirmed sepsis. Originally developed by the European Society of Intensive Care Medicine working group led by Jean-Louis Vincent in 1996, the SOFA score evaluates six organ systems to provide a comprehensive assessment of multi-organ dysfunction.

The six organ systems assessed are: respiratory (PaO2/FiO2 ratio), coagulation (platelet count), hepatic (bilirubin level), cardiovascular (mean arterial pressure and vasopressor requirements), neurological (Glasgow Coma Scale), and renal (creatinine level or urine output). Each system is scored from 0 (normal function) to 4 (severe dysfunction), yielding a total score ranging from 0 to 24.

The SOFA score gained particular prominence with the Sepsis-3 definitions published in 2016 (Singer et al., JAMA), which redefined sepsis as life-threatening organ dysfunction caused by a dysregulated host response to infection, operationalized as an acute change in SOFA score of 2 or more points due to infection. This definition made the SOFA score central to the modern diagnosis and classification of sepsis.

The initial SOFA score at ICU admission provides prognostic information about mortality risk. However, the most valuable clinical application is serial monitoring: trends in SOFA scores over the first 48-96 hours of ICU admission are more predictive of outcomes than any single measurement. An increasing SOFA score indicates worsening organ dysfunction and carries a particularly poor prognosis.

Each organ system component contributes independently to the overall score. The respiratory component uses the PaO2/FiO2 ratio, with mechanical ventilation as a qualifying factor for scores of 3 and 4. The cardiovascular component uniquely incorporates both hemodynamic parameters (MAP) and pharmacological support (type and dose of vasopressors), reflecting the critical distinction between spontaneous and supported cardiovascular function.

The SOFA score correlates well with ICU mortality across diverse patient populations. Scores of 0-1 are associated with less than 5% mortality. Scores of 2-6 carry 5-20% mortality. Scores of 7-9 are associated with 25-35% mortality. Scores of 10-12 carry 35-50% mortality, and scores above 12 are associated with mortality exceeding 50%, though individual patient outcomes depend on many factors beyond the SOFA score alone.

For Sepsis-3 diagnostic purposes, a quick SOFA (qSOFA) screening tool was developed using only bedside clinical findings (systolic BP, respiratory rate, and mental status) to identify patients outside the ICU who may be at risk for sepsis. The full SOFA score remains the definitive tool for ICU-level assessment and monitoring.

This calculator implements the complete six-organ SOFA scoring system with mortality estimates based on published validation studies across large ICU populations.