APACHE II Score Calculator
Calculate the APACHE II (Acute Physiology and Chronic Health Evaluation II) score to assess ICU patient severity and predict hospital mortality risk.
What is the APACHE II score?
APACHE II (Acute Physiology and Chronic Health Evaluation II) is a severity-of-disease classification system used in ICUs. It predicts hospital mortality based on 12 physiological measurements, age, and chronic health status, scored 0-71 points. Developed in 1985, it helps assess disease severity, predict outcomes, compare ICU performance, and guide resource allocation. Higher scores indicate higher mortality risk. Most ICU patients score 10-30; scores >40 suggest very high mortality risk.
How is the APACHE II score calculated?
APACHE II has three components: 1) Acute Physiology Score (0-60 points): 12 vital signs/lab values measured in first 24 hours, worst values used. Points assigned based on deviation from normal. 2) Age Points (0-6): 0 if <44, up to 6 if >=75. 3) Chronic Health Points (0-5): 2 points if history of severe organ insufficiency, 5 if post-emergency surgery. Total = sum of all three. Original study showed: score 0-4 = 4% mortality, 25-34 = 55% mortality, >34 = 85% mortality.
What lab values are needed for APACHE II?
Required measurements (worst value in first 24 hours): Temperature (rectal preferred), Mean Arterial Pressure (MAP), Heart Rate, Respiratory Rate, Oxygenation (A-aDO₂ if FiO₂>=0.5, else PaO₂), Arterial pH, Serum Sodium, Serum Potassium, Serum Creatinine (double points if acute renal failure), Hematocrit, White Blood Cell count, Glasgow Coma Scale (15 minus actual GCS). Not all patients need all tests; use available values, omitted variables score 0.
What does my APACHE II score mean?
Score interpretation: 0-4 points = 4% mortality (low risk), 5-9 = 8% (low-moderate), 10-14 = 15% (moderate), 15-19 = 25% (moderate-high), 20-24 = 40% (high), 25-29 = 55% (very high), 30-34 = 75% (severe), >=35 = 85%+ (critical). These are statistical averages; individual outcomes vary based on diagnosis, comorbidities, treatment response. Used for population-level predictions and ICU benchmarking, NOT definitive individual prognosis. Discuss with medical team for personalized interpretation.
How does APACHE II compare to other ICU scoring systems?
APACHE II vs others: APACHE III (1991) and IV (2006) are proprietary, more complex, potentially more accurate but require licensing. SAPS II (Simplified Acute Physiology Score) similar to APACHE II, widely used in Europe. SOFA (Sequential Organ Failure Assessment) focuses on organ dysfunction tracking over time. MODS, MPM also available. APACHE II advantages: Free, well-validated, widely used (good for comparisons), simpler than newer versions. Most ICUs use multiple scores for comprehensive assessment.