APACHE II

ICU admission severity scoring. Predicts hospital mortality. Used for ICU triage, research stratification, and quality benchmarking.

Indication

ICU admission severity scoring. Predicts hospital mortality. Used for ICU triage, research stratification, and quality benchmarking.

Criteria

id: temp; label: Temperature (°C); type: options; options: value: 4; label: ≥41; value: 3; label: 39–40.9; value: 1; label: 38.5–38.9; value: 0; label: 36–38.4; value: 1; label: 34–35.9; value: 2; label: 32–33.9; value: 3; label: 30–31.9; value: 4; label: <30
id: map; label: Mean Arterial Pressure (mmHg); type: options; options: value: 4; label: ≥160; value: 3; label: 130–159; value: 2; label: 110–129; value: 0; label: 70–109; value: 2; label: 50–69; value: 4; label: <50
id: hr; label: Heart Rate (bpm); type: options; options: value: 4; label: ≥180; value: 3; label: 140–179; value: 2; label: 110–139; value: 0; label: 70–109; value: 2; label: 55–69; value: 3; label: 40–54; value: 4; label: <40
id: rr; label: Respiratory Rate; type: options; options: value: 4; label: ≥50; value: 3; label: 35–49; value: 1; label: 25–34; value: 0; label: 12–24; value: 1; label: 10–11; value: 2; label: 6–9; value: 4; label: <6
id: oxygen; label: Oxygenation (A-aDO2 if FiO2≥0.5, else PaO2); type: options; options: value: 4; label: A-aDO2 ≥500; value: 3; label: A-aDO2 350–499; value: 2; label: A-aDO2 200–349; value: 0; label: A-aDO2 <200 or PaO2 >70; value: 1; label: PaO2 61–70; value: 3; label: PaO2 55–60; value: 4; label: PaO2 <55
id: ph; label: Arterial pH; type: options; options: value: 4; label: ≥7.7; value: 3; label: 7.6–7.69; value: 1; label: 7.5–7.59; value: 0; label: 7.33–7.49; value: 2; label: 7.25–7.32; value: 3; label: 7.15–7.24; value: 4; label: <7.15
id: sodium; label: Serum Sodium (mEq/L); type: options; options: value: 4; label: ≥180; value: 3; label: 160–179; value: 2; label: 155–159; value: 1; label: 150–154; value: 0; label: 130–149; value: 2; label: 120–129; value: 3; label: 111–119; value: 4; label: ≤110
id: potassium; label: Serum Potassium (mEq/L); type: options; options: value: 4; label: ≥7; value: 3; label: 6–6.9; value: 1; label: 5.5–5.9; value: 0; label: 3.5–5.4; value: 1; label: 3–3.4; value: 2; label: 2.5–2.9; value: 4; label: <2.5
id: creatinine; label: Serum Creatinine (mg/dL) — double if acute renal failure; type: options; options: value: 8; label: ≥3.5 (acute renal failure); value: 4; label: ≥3.5 (chronic); value: 6; label: 2–3.4 (acute); value: 3; label: 2–3.4 (chronic); value: 2; label: 1.5–1.9; value: 0; label: 0.6–1.4; value: 2; label: <0.6
id: hematocrit; label: Hematocrit (%); type: options; options: value: 4; label: ≥60; value: 2; label: 50–59.9; value: 1; label: 46–49.9; value: 0; label: 30–45.9; value: 2; label: 20–29.9; value: 4; label: <20
id: wbc; label: WBC (×1000/µL); type: options; options: value: 4; label: ≥40; value: 2; label: 20–39.9; value: 1; label: 15–19.9; value: 0; label: 3–14.9; value: 2; label: 1–2.9; value: 4; label: <1
id: gcs; label: Glasgow Coma Scale (points = 15 − GCS); type: options; options: value: 0; label: GCS 15; value: 1; label: GCS 14; value: 2; label: GCS 13; value: 3; label: GCS 12; value: 4; label: GCS 11; value: 5; label: GCS 10; value: 6; label: GCS 9; value: 7; label: GCS 8; value: 8; label: GCS 7; value: 9; label: GCS 6; value: 10; label: GCS 5; value: 11; label: GCS 4; value: 12; label: GCS 3
id: age; label: Age (years); type: options; options: value: 0; label: ≤44; value: 2; label: 45–54; value: 3; label: 55–64; value: 5; label: 65–74; value: 6; label: ≥75
id: chronic; label: Chronic Health (severe organ insufficiency / immunocompromise); type: options; options: value: 0; label: None; value: 2; label: Elective postoperative; value: 5; label: Nonoperative or emergency postoperative

Interpretation

function(score) { if (score <= 4) return { risk: score + ' pts', tier: 'Predicted mortality ~4%', action: 'Low severity. Routine ICU care.', color: 'green' }; if (score <= 9) return { risk: score + ' pts', tier: 'Predicted mortality ~8%', action: 'Low-moderate severity.', color: 'green' }; if (score <= 14) return { risk: score + ' pts', tier: 'Predicted mortality ~15%', action: 'Moderate severity. Close monitoring.', color: 'yellow' }; if (score <= 19) return { risk: score + ' pts', tier: 'Predicted mortality ~25%', action: 'Moderate-high severity.', color: 'yellow' }; if (score <= 24) return { risk: score + ' pts', tier: 'Predicted mortality ~40%', action: 'High severity. Aggressive ICU management.', color: 'red' }; if (score <= 29) return { risk: score + ' pts', tier: 'Predicted mortality ~55%', action: 'Very high severity.', color: 'red' }; if (score <= 34) return { risk: score + ' pts', tier: 'Predicted mortality ~73%', action: 'Critical severity. Goals-of-care discussion.', color: 'red' }; return { risk: score + ' pts', tier: 'Predicted mortality ~85%', action: 'Extreme severity. Maximal support; goals-of-care discussion.', color: 'red' }; }

Clinical pearls

APACHE II is a group-level predictor — do not use it to make individual triage or withdrawal decisions
APACHE IV is more accurate but considerably more complex
SOFA is preferred for tracking day-to-day organ dysfunction during the ICU stay
Double the creatinine points in the presence of acute renal failure

Source and review

Knaus WA et al. Crit Care Med 1985. Last reviewed: 2025-01-01