ICU severity scoring
Simplified Acute Physiology Score II (SAPS II)
Enter the most abnormal values in the first 24 hours of ICU admission. The calculator sums SAPS II points and provides predicted hospital mortality based on the original logistic equation.
Component points
- age12
- hr0
- sbp5
- temp0
- oxygen9
- urine4
- bun10
- wbc0
- potassium0
- sodium0
- bicarbonate3
- bilirubin0
- gcs4
- admission6
- chronic0
Total SAPS II
53
Points 0–163
SAPS II 50–64 indicates severe physiologic derangement. Monitor trends closely; consider referral to tertiary ICU if applicable.
Predicted hospital mortality: 53.0%
How to Use This Calculator
Collect worst values within first ICU day
Use the most abnormal measurement during the first 24 hours, not averages. Record timing for auditability.
Adjust units carefully
Ensure BUN is entered in mg/dL (the calculator internally converts to mmol/L). PaO₂/FiO₂ requires FiO₂ as fraction.
Interpret mortality in context
Predicted mortality stems from the original SAPS II cohort (1993). Compare with contemporary benchmarks and local outcomes.
Formula & Components
SAPS II total = Sum of points from age, 12 physiologic variables, type of admission, and chronic disease points (range 0–163).
Predicted mortality = elogit ÷ (1 + elogit), where logit = -7.7631 + 0.0737 × SAPS II + 0.9971 × ln(SAPS II + 1).
Higher scores indicate greater risk of hospital death.
Frequently Asked Questions
Does SAPS II apply to pediatric patients?
No. SAPS II is validated only in adults. Use pediatric-specific scores such as PRISM or PIM.
How do chronic diseases affect scoring?
Add points for AIDS (+17), metastatic cancer (+9), and hematologic malignancy (+10). Multiple conditions are additive.
Can I use arterial lactate instead of BUN?
No. SAPS II specifically uses blood urea nitrogen. Lactate is not part of the original score.
How often should SAPS II be recalculated?
SAPS II was designed for admission severity; it is not typically recalculated daily. Use SOFA or APACHE for longitudinal tracking.