What does a SAPS II score of 50 mean?

A SAPS II score of 50 corresponds to an estimated in-hospital mortality of roughly 40–50% according to the Le Gall 1993 logistic equation. Scores below 30 suggest low risk; scores above 60 are associated with very high mortality. All estimates reflect the original derivation cohort and may differ in modern ICUs.

How is the mortality probability calculated?

The logistic regression formula from Le Gall et al. 1993 is: logit = −7.7631 + 0.0737 × SAPS_II + 0.9971 × ln(SAPS_II + 1). Mortality probability = e^logit / (1 + e^logit). This tool calculates and displays that figure automatically.

Which value do I use when a parameter fluctuates over 24 hours?

Use the WORST (most abnormal) value recorded during the first 24 hours of ICU admission. For GCS, use the lowest score — if the patient is sedated, many institutions record the estimated pre-sedation GCS or use 15 by protocol. Follow your unit guideline.

How does SAPS II differ from APACHE II?

SAPS II (17 variables, derived 1993) and APACHE II (12 APS variables + age + chronic health, derived 1985) are both widely used ICU severity scores. SAPS II is generally considered simpler to collect and was derived from a larger multinational European cohort. Both are population-level mortality estimators, not individual predictors.

What is the PaO2/FiO2 ratio and how do I calculate it?

PaO2/FiO2 (P/F ratio) is the arterial partial pressure of oxygen divided by the inspired oxygen fraction. Example: PaO2 = 80 mmHg, FiO2 = 0.40 → P/F = 200. It is only scored when the patient is on mechanical ventilation or CPAP. If not ventilated, this variable is not included.

Is this tool a substitute for clinical judgment?

No. SAPS II is a research and educational tool that provides population-level risk estimates. It must be interpreted by qualified clinicians with full knowledge of the patient's presentation and course. Never use any score alone to make treatment, triage, or end-of-life decisions.

SAPS II Score Calculator

Name: SAPS II Score Calculator
Availability: InStock
Author: Nham Vu

Enter 17 physiological variables from the first 24 hours of ICU admission to calculate the SAPS II score and estimated in-hospital mortality.

For educational use only. Use the worst value from the first 24 hours of ICU admission. Not a substitute for clinical judgment — all scores must be interpreted by qualified clinicians.

A Physiological Variables (first 24 h)

Enter the worst (most abnormal) value recorded in the first 24 hours of ICU admission.

1. Age (years)

< 40 = 0 pts • 40–59 = 7 pts • 60–69 = 12 pts • 70–74 = 15 pts • 75–79 = 16 pts • ≥ 80 = 18 pts

2. Heart Rate (beats/min)

< 40 = 11 pts • 40–69 = 2 pts • 70–119 = 0 pts • 120–159 = 4 pts • ≥ 160 = 7 pts

3. Systolic Blood Pressure (mmHg)

< 70 = 13 pts • 70–99 = 5 pts • 100–199 = 0 pts • ≥ 200 = 2 pts

4. Body Temperature (°C)

< 39 = 0 pts • ≥ 39 = 3 pts

5. Glasgow Coma Scale (GCS) — Total

< 6 = 26 pts • 6–8 = 13 pts • 9–10 = 7 pts • 11–13 = 5 pts • 14–15 = 0 pts

6. Oxygenation

Patient is on mechanical ventilation or CPAP

Not ventilated — PaO₂/FiO₂ is not scored.

7. Urine Output (mL / 24 hours)

< 500 = 11 pts • 500–999 = 4 pts • ≥ 1000 = 0 pts

8. Blood Urea Nitrogen (mg/dL)

< 28 = 0 pts • 28–83 = 6 pts • ≥ 84 = 10 pts

9. Serum Sodium (mEq/L)

< 125 = 5 pts • 125–144 = 0 pts • ≥ 145 = 1 pt

10. Serum Potassium (mEq/L)

< 3.0 = 3 pts • 3.0–4.9 = 0 pts • ≥ 5.0 = 3 pts

11. Serum Bicarbonate (mEq/L)

< 15 = 6 pts • 15–19 = 3 pts • ≥ 20 = 0 pts

12. Total Bilirubin (mg/dL)

< 4.0 = 0 pts • 4.0–5.9 = 4 pts • ≥ 6.0 = 9 pts

13. White Blood Cell Count (×10³/mm³)

< 1.0 = 12 pts • 1.0–19.9 = 0 pts • ≥ 20.0 = 3 pts

B Admission Type

Medical: 0 pts Scheduled (elective) surgical: −6 pts Unscheduled (emergency) surgical: +6 pts

C Chronic Disease (select at most one)

None: 0 pts Metastatic cancer: 9 pts Hematologic malignancy: 10 pts AIDS: 17 pts

Complete the parameters on the left
and click Calculate.

SAPS II Score — Predicted Mortality Reference

SAPS II Score	Estimated Mortality	Risk Category
< 20	~2%	Very Low
20–29	~5–10%	Low
30–39	~15–20%	Moderate
40–49	~25–35%	High
50–59	~40–50%	High
60–69	~60–70%	Very High
≥ 70	> 75%	Critical

Source: Le Gall JR et al., JAMA 1993. Mortality estimates are approximate and reflect the original derivation cohort. Modern ICU outcomes may differ.

Summary

Enter 17 physiological variables from the first 24 hours of ICU admission to calculate the SAPS II score and estimated in-hospital mortality.

How it works

Enter each of the 17 variables recorded during the first 24 hours of ICU admission.
Use the worst (most abnormal) value for each parameter over that 24-hour window.
For urine output, enter the total volume produced over the full 24-hour period.
Select the admission type and any applicable chronic disease (metastatic cancer, hematologic malignancy, or AIDS).
Click Calculate to obtain the total SAPS II score and estimated in-hospital mortality.
Review the variable-by-variable breakdown to identify the largest contributors to the score.

Use cases

Estimate ICU admission severity and predicted in-hospital mortality for critically ill patients.
Benchmark ICU performance and risk-adjust outcomes for quality-improvement analysis.
Communicate patient acuity to intensivists, nurses, and consultants during handover.
Support goals-of-care discussions with estimated mortality probabilities.
Screen patients for clinical trial eligibility that specifies a SAPS II threshold.
Teach medical students and residents systematic critical illness assessment.
Compare severity-adjusted mortality between ICU cohorts in research.
Track physiological trajectory when the score is recalculated serially.

Frequently Asked Questions

Last updated: 2026-07-24 · Reviewed by Nham Vu