APACHE II Score Calculator (Acute Physiology and Chronic Health Evaluation II)
Calculate ICU mortality risk based on 12 physiological measurements. Includes standard 1985 Knaus logic for precise clinical assessment.
A. Physiological Variables (Worst in 24h)
B. Patient Profile
About
The Acute Physiology and Chronic Health Evaluation II (APACHE II) is a severity-of-disease classification system used in intensive care units. It quantifies the severity of illness to estimate the risk of in-hospital mortality. This tool is designed for intensivists and critical care nurses who require rapid, error-free scoring during rounds. Incorrect risk stratification can lead to inappropriate resource allocation or miscommunication regarding prognosis. This implementation adheres strictly to the 1985 Knaus et al. guidelines, summing points from acute physiological variables, age, and chronic health status.
Formulas
The total score is the sum of three components:
The predicted mortality rate (R) is derived using the logistic regression equation:
Where APS (Acute Physiology Score) sums weights from 12 physiological variables derived from the worst values in the first 24 hours of admission.
Reference Data
| Score Range | Approximate Hospital Mortality | Interpretation |
|---|---|---|
| 0 - 4 | 4% | Non-operative / Post-operative surveillance |
| 5 - 9 | 8% | Low risk, monitor for deterioration |
| 10 - 14 | 15% | Moderate risk |
| 15 - 19 | 25% | Significant physiological derangement |
| 20 - 24 | 40% | High mortality risk |
| 25 - 29 | 55% | Severe illness |
| 30 - 34 | 73% | Critical condition |
| ≥35 | 85% + | Extreme risk, outcome likely fatal |