Calculate the Sequential Organ Failure Assessment (SOFA) score for ICU patients. Measures organ dysfunction across 6 systems and predicts ICU mortality under Sepsis-3.
The Sequential Organ Failure Assessment (SOFA) score is the cornerstone of organ dysfunction assessment in the intensive care unit. Originally created by Vincent et al. in 1996, it evaluates six organ systems — respiration, coagulation, liver, cardiovascular, central nervous, and renal — each scored 0-4 based on the degree of dysfunction, yielding a total score from 0 to 24.
SOFA gained central importance in the Sepsis-3 consensus (2016), which defined sepsis as "life-threatening organ dysfunction caused by a dysregulated host response to infection," operationalized as a SOFA increase ≥2 points from baseline in the presence of infection. This replaced the older SIRS-based definition, recognizing that organ dysfunction is the critical element that distinguishes sepsis from uncomplicated infection.
Beyond sepsis diagnosis, SOFA is used daily in ICUs worldwide for prognostication, monitoring response to therapy, and quality benchmarking. Serial SOFA scores (delta-SOFA) over the first 48-96 hours of ICU admission are among the strongest predictors of ICU outcome — a rising SOFA portends poor prognosis, while a falling SOFA indicates clinical improvement.
SOFA provides a standardized, objective measure of organ dysfunction that transcends individual parameters. While a single lab value (creatinine, bilirubin) reflects one organ, SOFA integrates information across all six vital organ systems, capturing the multisystem nature of critical illness.
The daily SOFA trend (delta-SOFA) is particularly powerful: patients whose SOFA worsens by ≥2 points over 48 hours have mortality rates exceeding 50%, providing a quantitative basis for escalation of care or goals-of-care discussions.
SOFA Score = Sum of 6 organ subscores (each 0-4) Range: 0-24 Respiration: PaO₂/FiO₂ (mmHg) Coagulation: Platelets (×10³/μL) Liver: Bilirubin (mg/dL) Cardiovascular: MAP or vasopressor requirement CNS: Glasgow Coma Scale Renal: Creatinine (mg/dL) or urine output Sepsis-3: Infection + SOFA ≥2 = Sepsis Septic shock: Sepsis + vasopressor for MAP ≥65 + lactate >2
Result: SOFA Score 11 — Mortality 40-50%
Resp 3 + Coag 1 + Liver 0 + CV 3 + CNS 2 + Renal 2 = 11/24. Three organ systems have significant dysfunction (≥2), indicating multi-organ failure. Cardiovascular and respiratory systems are most severely affected. If this SOFA represents a ≥2 point increase from baseline with suspected infection, sepsis is diagnosed. The patient requires aggressive ICU management.
The Third International Consensus Definitions for Sepsis (Sepsis-3, 2016) placed SOFA at the center of sepsis diagnosis. Sepsis = suspected infection + SOFA ≥2 from baseline. Septic shock = sepsis requiring vasopressors for MAP ≥65 + serum lactate >2 mmol/L despite adequate fluid resuscitation. This definition emphasizes that organ dysfunction is the defining feature of sepsis, not just infection with an inflammatory response.
Studies consistently show that the SOFA trajectory is more informative than the admission score: Improving SOFA (decrease ≥2 in 48h): <10% mortality. Stable SOFA: ~20-30% mortality. Worsening SOFA (increase ≥2 in 48h): >50% mortality. Maximum SOFA during the ICU stay correlates most strongly with outcome.
Modified SOFA (mSOFA): Uses SpO₂/FiO₂ instead of PaO₂/FiO₂ for settings without ABGs. qSOFA: 3-item bedside screen (SBP, RR, GCS) for non-ICU settings. Pediatric SOFA (pSOFA): Age-adjusted thresholds for children. Neonatal SOFA (nSOFA): Adapted for neonatal physiology.
For patients without known pre-existing organ dysfunction, baseline SOFA is assumed to be 0. For patients with chronic organ dysfunction (e.g., chronic kidney disease, cirrhosis), the baseline should be estimated from their chronic lab values. A SOFA increase ≥2 from this baseline in the setting of infection meets Sepsis-3 criteria.
In most ICUs, SOFA is calculated daily using the worst values from the preceding 24 hours. Some protocols calculate it every 6-12 hours for actively deteriorating patients. The trend (delta-SOFA) over 48-96 hours is more prognostically valuable than any single score.
SOFA was developed and validated in the ICU setting. For non-ICU patients (ED, floor), qSOFA is recommended as a screening tool. If qSOFA ≥2, the patient should be assessed for organ dysfunction (ideally with SOFA) and considered for ICU-level care. Some studies have applied SOFA in the ED with good results.
Cardiovascular SOFA 3-4 indicates the patient requires vasopressor support: score 3 = dopamine >5 or any epinephrine/norepinephrine ≤0.1 mcg/kg/min; score 4 = dopamine >15 or epi/norepi >0.1 mcg/kg/min. These patients have distributive, cardiogenic, or vasodilatory shock requiring pharmacological circulatory support.
APACHE-II uses 12+ physiological variables, age, and chronic health factors, calculated once at ICU admission. SOFA uses 6 organ-specific parameters, calculated daily. APACHE-II is better for admission prognosis and case-mix adjustment. SOFA is better for tracking organ dysfunction trajectory over time. Both are complementary.
SOFA alone should never determine withdrawal of care. While high SOFA scores correlate with high mortality, individual patients may surpass statistical predictions. SOFA provides objective data to inform goals-of-care discussions with families and multidisciplinary teams, but ethical, cultural, and individual factors must always be considered.