APACHE Score Cut-Off Point for Predicting Mortality
The APACHE II score of 8 or higher is the optimal cut-off point for predicting mortality, with a sensitivity of 83.3% and specificity of 91%. 1
Understanding APACHE II Score
The Acute Physiology and Chronic Health Evaluation II (APACHE II) score is a widely validated instrument used to predict mortality in critically ill patients. It evaluates:
- 12 physiological measurements 1
- Chronic health score 1
- Can be calculated at any time during patient care 1
Evidence for Cut-Off Points
For General Critical Care:
- APACHE II ≥ 8 is the significant cut-off value for predicting severe acute pancreatitis and mortality 1
- APACHE II score demonstrates 55.6% positive predictive value after 48 hours with 83.3% sensitivity and 91% specificity 1
For Specific Conditions:
- In sepsis: APACHE II score ≥ 26 shows very good discriminatory performance with 75% accuracy and AUC-ROC of 0.80 (95% CI: 0.74-0.85) 2
- In respiratory ICU patients: APACHE II outperformed SAPS II with area under ROC curve of 80.88% (SE 2.89%) 3
Mortality Risk Stratification
Recent evidence suggests the following mortality risk stratification based on APACHE II scores:
- APACHE II score 21-30: extremely high mortality (100% in some studies) 4
- APACHE II score 31-40: extremely high mortality (100% in some studies) 4
- APACHE II score 11-20: moderate mortality (approximately 28.45%) 4
- APACHE II score 3-10: low mortality 4
Advantages and Limitations
Advantages:
- Widely validated instrument across multiple conditions 1
- Can be calculated at any time during patient care 1
- Demonstrates high accuracy for mortality prediction 5
Limitations:
- Cumbersome calculation process 1
- Not all required parameters are routinely collected 1
- Not designed for day-to-day evaluation in any patient 1
- May perform differently across specific conditions (e.g., cardiac pulmonary edema) 6
Clinical Application
When using APACHE II for mortality prediction:
- Calculate within the first 24 hours of ICU admission for optimal predictive value 4
- Consider using APACHE II ≥ 8 as the general cut-off point for increased mortality risk 1
- Be aware that disease-specific cut-offs may vary (e.g., ≥ 26 for sepsis) 2
- Use as an early warning system to potentially upgrade treatment protocols 4
Comparison with Other Scoring Systems
- APACHE II demonstrated higher accuracy for predicting severe acute pancreatitis compared to Ranson, BISAP, and CTSI scores 1
- APACHE II outperformed SAPS II in respiratory ICU patients 3
- APACHE IV showed excellent accuracy for mortality prediction with optimal cut-off of 78.9 (sensitivity 0.96, specificity 0.96) 5
- In elderly trauma patients, APACHE III (AUC 0.783) outperformed GTOS (AUC 0.683) for predicting mortality in ICU patients 1