Simplified Acute Physiology Score (SAPS II)

Evaluates health status at the start of ICU admission and predicts mortality risk.

In the text below the calculator there is more information about the formula used and about the original study.

The simplified acute physiology score consists of 15 items that assess the severity of health in patients from intensive care units, within 24h from admission. 

It provides a numeric result which is then transformed (via a formula) in a mortality risk percentage.

SAPS II was found to be more accurate than APACHE II and is often used in studies when comparing mortality rates.

The mortality prediction offered by SAPS II employs the score from the 15 items in the following formulas:

logit = −7.7631 + 0.0737 x Score + 0.9971 x ln (Score + 1)

Mortality = elogit/(1+elogit) x 100


Age (years)


Type of admission


Heart rate (bpm)


Systolic blood pressure (mmHg)


Temperature (C or F)


Glagow coma score


PaO2 (mmHg)/FiO2 (%) if mechanical ventilation or CPAP


Urine output (L/24h)


Serum Urea (g/L) or BUN (mg/dL)


Sodium (mEq/L)


Potassium (mEq/L)


Bicarbonate (mEq/L)


Bilirubin (mg/dL)


White blood cells/mm3


Chronic diseases

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SAPS II explained

This is a disease severity classification system that is used for assessment of adult patients in intensive care units across the world.

Data required in the 15 items of the score is either readily available (e.g. patient age, type of admission, chronic diseases), refers to vital signs regularly monitored (e.g. heart rate, systolic blood pressure, temperature) or is determined within 24 hours.

The following table describes the 15 items of the score with respect to their value in assessing health status:

SAPS II items Description
Patient age Higher age means higher risk of severe health.
Heart rate Accounts for the worst value in beats per minute.
Systolic blood pressure Accounts for the highest or lowest value, whichever is the worst, meaning either hypertension or hypotension.
Glasgow coma scale Lowest value in the first assessment after admission and before any sedation procedure occurs.
Body temperature Measured in degrees Celsius or Fahrenheit, with a cut off at 39C/102.2F.
PaO2/FiO2 ratio If the patient is under mechanical or continuous positive airway pressure (CPAP) ventilation.
Urinary output From the past 24 hours.
Serum urea or BUN Whichever is measured and if both, the highest one is considered.
White blood cells count Cells per mm3, the lowest or the highest measurement, the one most indicative of severe status.
Serum potassium Part of the metabolic panel.
Serum sodium Offers information about hyponatremia.
Serum bicarbonate Checks electrolyte balance.
Bilirubin Checks integrity of renal function.
Chronic diseases - Metastatic cancer (proven by surgery or CT scan)
- Hematologic malignancy (if lymphoma, acute leukemia, or multiple myeloma)
- HIV positive patient

The scoring method provides an integer point score between 0 and 163 which is then correlated to mortality rates given in percentage (between 0 and 100%).

SAPS II was found to be more accurate than APACHE II, a similar intensive care classification score, and is commonly used in studies to compare morbidity and outcomes between patients.


Mortality rates correlated with SAPS II

The mortality prediction offered by SAPS II is based on the following two formulas that employ the integer result (from the assessment of the 15 items) and certain study based variables:

logit = −7.7631 + 0.0737 x Score + 0.9971 x ln (Score + 1)

Mortality = elogit / (1+elogit) x 100

The following table provides examples of the SAPS II scores that are associated with different mortality rates:

SAPS II score Mortality rate
29 10%
40 25%
52 50%
64 75%
77 90%
≥142 100%

A similar mortality prediction for patients in intensive care units can be obtained via the Sequential Organ Failure Assessment (SOFA score).


About the study

In 1993, Le Gall et al. analysed data from 13,152 consecutive admissions to 137 adult medical and/or surgical intensive care units in 12 countries.

Two groups were formed, one developmental (65%) and one for validation (35%) and the outcome measure was set as vital status at hospital discharge. The study excluded patients younger than 18, patients in cardiac care or who underwent cardiac surgery, as well as burn patients, were excluded.

Goodness-of-fit tests indicated that the model performed well in both samples. The under the receiver operating characteristic curve was 0.88 for development group and 0.86 in the validation group.

The SAPS II provides an accurate estimate of risk of death and can provide a starting point for devising care strategy in ICU.


Original source

Le Gall J-R, Lemeshow S, Saulnier F. A New Simplified Acute Physiology Score (SAPS II) Based on a European/North American Multicenter Study. JAMA. 1993; 270:2957-2963.

Other references

1. Deša K, Perić M, Husedžinović I et al. Prognostic performance of the Simplified Acute Physiology Score II in major Croatian hospitals: a prospective multicenter study. Croat Med J. 2012; 53(5): 442–449.

2. Le Gall J-R, Neumann A, Hemery F et al. Mortality prediction using SAPS II: an update for French intensive care units. Crit Care. 2005; 9(6): R645–R652.

3. Gilani MT, Razavi M, Azad AM. (2014) A comparison of Simplified Acute Physiology Score II, Acute Physiology and Chronic Health Evaluation II and Acute Physiology and Chronic Health Evaluation III scoring system in predicting mortality and length of stay at surgical intensive care unit. Niger Med J. 2014; 55(2): 144–147.

Specialty: Emergency

Objective: Mortality Prediction

Type: Score

No. Of Items: 15

Year Of Study: 1993

Abbreviation: SAPS II

Article By: Denise Nedea

Published On: June 20, 2017

Last Checked: June 20, 2017

Next Review: June 20, 2023