About the APACHE II Score
The Acute Physiology and Chronic Health Evaluation II (APACHE II) was published by Knaus et al. in 1985 and remains one of the most widely validated and used ICU scoring systems in the world. It estimates the probability of in-hospital mortality based on 12 acute physiological variables, patient age, and chronic health status, assessed within the first 24 hours of ICU admission.
APACHE II Predicted Mortality Reference
| APACHE II Score | Non-Surgical ICU Mortality | Post-Emergency Surgery |
|---|---|---|
| 0–4 | ~4% | ~1% |
| 5–9 | ~8% | ~3% |
| 10–14 | ~15% | ~7% |
| 15–19 | ~25% | ~12% |
| 20–24 | ~40% | ~30% |
| 25–29 | ~55% | ~35% |
| 30–34 | ~73% | ~73% |
| ≥35 | ~85% | ~88% |
Limitations
- APACHE II was derived from 1979–1982 ICU data — case mix, treatments, and outcomes have changed significantly since then.
- It is designed for group mortality prediction (populations), not individual patient prognosis.
- Diagnosis-specific mortality may differ substantially from the overall predicted mortality.
- Other systems (APACHE III, APACHE IV, SOFA, SAPS II) may be more accurate for specific populations or contemporary practice.
- APACHE II should never be used as a basis for withdrawal of care decisions for individual patients.
Related Tools on MediCalc Pro
For neurological assessment in ICU patients, see Glasgow Coma Scale. For pneumonia severity and ICU admission criteria, see CURB-65 Score. For sepsis-related coagulopathy assessment, see CHA₂DS₂-VASc for anticoagulation decisions. For renal replacement therapy indication, see Creatinine Clearance. For IV fluid rate and vasopressor dose calculations, see IV Drip Rate Calculator and Weight-Based Dose Calculator.
References
- Knaus WA, et al. "APACHE II: A severity of disease classification system." Crit Care Med. 1985;13(10):818-829.
- Zimmerman JE, et al. "Acute Physiology and Chronic Health Evaluation (APACHE) IV: Hospital mortality assessment for today's critically ill patients." Crit Care Med. 2006;34(5):1297-1310.