SAPS II Calculator: Simplified Acute Physiology II Score Calculator

Score the SAPS II severity index from 12 physiological variables, age, Glasgow Coma Scale, admission type, and chronic disease, then read the logistic-regression estimate of hospital mortality.

Quick Facts

Score range
0 to about 163 points
Sum of age, 12 physiological variables, Glasgow Coma Scale, admission type, and chronic disease points.
Timing
First 24 hours in the ICU
Enter the worst recorded value for each variable during that window.
Mortality model
Logistic regression
logit = -7.7631 + 0.0737 x score + 0.9971 x ln(score + 1).

Your Results

Calculated
SAPS II score
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Total points (0-163)
Physiology + age + GCS
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12 vitals/labs + age + GCS subtotal
Admission + chronic disease
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Type of admission + chronic disease points
Predicted hospital mortality
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Logistic-regression estimate

Ready

Enter the worst first-24-hour ICU values, then calculate the SAPS II score.

About the SAPS II score

SAPS II (Simplified Acute Physiology Score II) is a severity-of-illness score used in intensive care. Published by Le Gall, Lemeshow, and Saulnier in 1993, it is one of the most widely used ICU scoring systems worldwide. The score is built from the worst physiological measurements recorded during a patient's first 24 hours in the ICU and produces a single number, typically 0 to around 163, that rises with the severity of acute illness.

How the score is built

The total sums points from several groups of variables, each compared against fixed bands:

  • Age: 0 points under 40, rising in steps to 18 points at 80 and older.
  • Twelve physiological variables: heart rate, systolic blood pressure, body temperature, PaO2/FiO2 ratio (scored only if the patient is mechanically ventilated or on CPAP), urine output, blood urea nitrogen, white blood cell count, serum potassium, serum sodium, serum bicarbonate, and total bilirubin.
  • Glasgow Coma Scale: 0 points for a GCS of 14-15, up to 26 points for a GCS under 6.
  • Type of admission: 0 points for scheduled surgical, 6 for medical, 8 for unscheduled surgical.
  • Chronic disease: 9 points for metastatic cancer, 10 for hematologic malignancy, or 17 for AIDS; 0 if none apply.

Adding every band together gives the total SAPS II score.

From score to predicted mortality

The original study converts the score into a predicted probability of hospital death using a logistic regression equation: logit = -7.7631 + 0.0737 x (SAPS II score) + 0.9971 x ln(SAPS II score + 1). The predicted mortality is then e^logit divided by (1 + e^logit), expressed as a percentage. Higher scores translate into a steadily higher predicted mortality, though the relationship is not linear.

When to consult a professional

This tool performs the standard SAPS II arithmetic and logistic-regression conversion for education and record-keeping. It is not a diagnosis and does not direct treatment. Any clinical decision should rest with the treating team, who interpret the score alongside the diagnosis, trends over time, and the whole clinical picture.

Frequently Asked Questions

What is the SAPS II score and what range does it use?
SAPS II (Simplified Acute Physiology Score II) is an ICU severity-of-illness score published by Le Gall and colleagues in 1993. It sums points from 12 physiological variables, age, Glasgow Coma Scale, type of admission, and three chronic disease categories, using the worst values from the first 24 hours after ICU admission. The total ranges from 0 to about 163 points, and higher scores indicate more severe illness.
How is the SAPS II score calculated?
Each variable is compared against fixed bands and assigned points: age (0-18), heart rate, systolic blood pressure, temperature, PaO2/FiO2 ratio if ventilated, urine output, blood urea nitrogen, white blood cell count, potassium, sodium, bicarbonate, and bilirubin, plus Glasgow Coma Scale (0-26). Points are added for type of admission (scheduled surgical, unscheduled surgical, or medical) and for chronic disease (metastatic cancer, hematologic malignancy, or AIDS). Summing every band gives the total SAPS II score.
How is predicted mortality calculated from the SAPS II score?
The SAPS II score feeds a logistic regression equation from the original study: logit = -7.7631 + 0.0737 x (SAPS II score) + 0.9971 x ln(SAPS II score + 1). Predicted probability of hospital death equals e^logit divided by (1 + e^logit). This is a population-derived estimate, not an individual prognosis, and should be interpreted by a clinician alongside diagnosis and trajectory.

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