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Acute Physiology and Chronic Health Evaluation II - Predict ICU mortality risk
Estimated Hospital Mortality:
Low mortality risk. Continue standard ICU care and monitoring.
APACHE II is for ICU mortality prediction only. Use alongside clinical judgment for individual patient care decisions.
| Variable | Range | Points |
|---|---|---|
| Age | <45, 45-54, 55-64, 65-74, ≥75 | 0, 2, 3, 5, 6 |
| Temperature | 30-41°C (abnormal values score higher) | 0-4 |
| MAP | 50-160+ mmHg | 0-4 |
| Heart Rate | 40-180+ bpm | 0-4 |
| Respiratory Rate | 6-50+ breaths/min | 0-4 |
| Oxygenation | A-a gradient or PaO2 | 0-4 |
| Arterial pH | 7.15-7.7 | 0-4 |
| Serum Sodium | 111-180 mEq/L | 0-4 |
| Serum Potassium | 2.5-7+ mEq/L | 0-4 |
| Creatinine | <1.5-3.5+ mg/dL | 0-4 |
| Hematocrit | 20-60% | 0-4 |
| WBC Count | 1-40 ×1000/μL | 0-4 |
| Glasgow Coma Scale | 3-15 (15 minus actual GCS) | 0-12 |
| Chronic Health | None, Elective surgery, Emergency/Nonop | 0, 2, 5 |
Predicts hospital mortality for ICU patients. Most accurate when calculated within 24 hours of ICU admission using worst values.
Helps guide ICU bed allocation, staffing levels, and intensive care resource distribution during capacity constraints.
Benchmark ICU performance by comparing predicted vs actual mortality. Used for quality assurance and research standardization.
Standardizes patient severity in critical care research. Widely used for patient matching and outcome prediction models.
Use worst physiological values from first 24 hours of ICU admission. Earlier calculation may underestimate severity.
Predicts group mortality, not individual outcomes. Cannot determine care ceiling for specific patients.
Should not be used alone to withhold or withdraw care. Clinical judgment and patient wishes remain paramount.
Severe organ insufficiency or immunocompromise. Includes liver, cardiac, respiratory, renal failure, or immunosuppression.
APACHE II (Acute Physiology and Chronic Health Evaluation II) is a severity-of-disease classification system that predicts hospital mortality for ICU patients. It combines 12 physiological measurements, age, and chronic health status into a score ranging from 0-71. Higher scores indicate greater disease severity and increased mortality risk. It's used for risk stratification, quality improvement, and research standardization.
APACHE II should be calculated within the first 24 hours of ICU admission using the worst physiological values recorded during that period. This timing provides the most accurate mortality prediction. Earlier calculations may underestimate disease severity, while later calculations may be influenced by treatment effects.
Chronic health points are added for severe organ system insufficiency or immunocompromise present before hospital admission. This includes cirrhosis with portal hypertension, NYHA Class IV heart failure, severe COPD, chronic dialysis, or immunosuppression from therapy or disease. Award 5 points for nonoperative or emergency surgery patients, or 2 points for elective postoperative patients.
APACHE II has good discriminative ability with AUC-ROC around 0.80-0.85 for hospital mortality prediction. However, it predicts mortality for groups of patients, not individuals. Two patients with identical scores may have different outcomes based on diagnosis, treatment response, and other factors not captured by the score.
No. APACHE II should never be used alone to make end-of-life decisions. It provides population-based mortality estimates, not individual prognosis. Care decisions must incorporate clinical judgment, patient trajectory, treatment response, patient/family wishes, and quality of life considerations. The score is one tool among many for assessing illness severity.
APACHE II (published 1985) remains widely used due to simplicity and validation. APACHE III (1991) and IV (2006) added more variables and diagnostic categories for improved accuracy but require proprietary software. APACHE II's free availability and extensive validation make it the most commonly used version in clinical practice and research.
APACHE II was developed for general ICU populations but has limitations. It performs less well in certain subgroups like cardiac surgery patients, burns, or trauma. Specialized scoring systems may be more appropriate for specific populations. The score is most validated for medical and emergency surgical ICU patients.
APACHE II was developed by Knaus et al. in 1985 as a simplified version of the original APACHE score. It uses 12 routine physiological measurements, reducing data collection burden while maintaining predictive accuracy. It remains the most widely used ICU severity scoring system globally.
The score has three components: Acute Physiology Score (0-60 points from 12 variables), Age Points (0-6), and Chronic Health Points (0-5). Total ranges from 0-71. Each physiological variable is scored based on deviation from normal, with more abnormal values receiving higher points.
Use APACHE II alongside other assessments like SOFA score for organ dysfunction tracking, clinical examination, imaging, and laboratory trends. It provides objective severity assessment but should never replace clinical judgment or patient-centered care discussions.
This APACHE II calculator is for educational and informational purposes only. It should not be used as the sole basis for clinical decisions. Always consult with qualified healthcare providers and use comprehensive clinical assessment when managing critically ill patients. APACHE II predicts population mortality, not individual outcomes.