Clinical meaning
Severity scoring systems are standardized tools used in critical care to quantify illness severity, predict mortality, guide treatment intensity, and facilitate quality benchmarking. Two of the most widely used are SOFA and APACHE II.
SOFA Score (Sequential Organ Failure Assessment): Assesses dysfunction in 6 organ systems, each scored 0-4 (total 0-24):
1. Respiratory: PaO2/FiO2 ratio • 0 = ≥400, 1 = <400, 2 = <300, 3 = <200 (with ventilatory support), 4 = <100 (with ventilatory support)
2. Coagulation: Platelet count (×10³/µL) • 0 = ≥150, 1 = <150, 2 = <100, 3 = <50, 4 = <20
3. Liver: Bilirubin (mg/dL) • 0 = <1.2, 1 = 1.2-1.9, 2 = 2.0-5.9, 3 = 6.0-11.9, 4 = >12.0
4. Cardiovascular: Mean Arterial Pressure / Vasopressor dose • 0 = MAP ≥70, 1 = MAP <70, 2 = Dopamine ≤5 or Dobutamine any, 3 = Dopamine >5 or Epi ≤0.1 or Norepi ≤0.1, 4 = Dopamine >15 or Epi >0.1 or Norepi >0.1
5. CNS: Glasgow Coma Scale • 0 = 15, 1 = 13-14, 2 = 10-12, 3 = 6-9, 4 = <6
6. Renal: Creatinine (mg/dL) or urine output • 0 = <1.2, 1 = 1.2-1.9, 2 = 2.0-3.4, 3 = 3.5-4.9 or UO <500mL/day, 4 = >5.0 or UO <200mL/day
Sepsis-3 Definition: An acute increase of ≥2 SOFA points from baseline + known/suspected infection = SEPSIS. SOFA score ≥2 has an overall mortality of approximately 10%.
APACHE II (Acute Physiology and Chronic Health Evaluation): Scored 0-71 based on 12 physiologic variables (worst values in first 24 hours of ICU admission), age points, and chronic health points. Higher scores = higher predicted mortality. Used for ICU admission risk stratification and outcomes research.