SAPS II Calculator

Simplified Acute Physiology Score (SAPS) II calculator to predict hospital mortality

Use the worst value for each physiological variable within the past 24 hours.
Heart rate Question
Systolic BP
Temp Question
Glasgow coma score Question
Mechanical ventilation or CPAP
Urine output
Chronic diseases Question
Type of admission Question
US units
Press 'Calculate' to view calculation results.

About This Calculator

The Simplified Acute Physiology Score (SAPS II) is a severity score and mortality estimation tool developed from a large sample of medical and surgical patients in North America and Europe.1

Sample Inclusion and Exclusion

The study analyzed a total of 12,997 patients from 137 medical, surgical, or mixed intensive care units in 12 countries from 9/30/1991 to 12/27/1991. Patients with burn injuries, coronary care unit patients, and cardiac surgery patients were excluded from analysis.

Study Variables

The SAPS II score is made of 12 physiological variables and 3 disease-related variables. The worst physiological variables were collected within the first 24 hours of ICU admission. The "worst" measurement was defined as the measure that correlated to the highest number of points. The study did not continually calculate SAPS II scores beyond the first 24 hours of ICU admission. The SAPS II score ranges from 0 to 163 points.

Correlation of Total Score and Hospital Mortality

Hospital mortality may be calculated using the following equation:

$$ \\ logit = -7.7631 + 0.0737*Score + 0.9971*ln(Score+1) \\ Mortality = \frac{e^{logit}}{1+e^{logit}} $$

Ability to Predict Hospital Mortality

The study used a pre-defined 65% of the patient population to define the SAPS II criteria, and the remaining 35% for validation purposes. The area under the ROC curve in the validation group was 0.86 (95% CI: 0.84 to 0.88). This AUC was considered superior to the previous SAPS score, which demonstrated an AUC ROC of 0.80.

Note that there is a sigmoidal relationship between mortality and the total SAPS II score, as demonstrated by the graph below:

SAPS II mortality increases in a sigmoid relationship.  29 points correlates to 10% mortality, 40 pts to 25% mortality, 52 pts to 50% mortality, 64 pts to 75% mortality, and 77 pts to 90% mortality.
Mortality SAPS II Score
10% 29 pts
25% 40 pts
50% 52 pts
75% 64 pts
90% 77 pts

References and Additional Reading

  1. Le Gall JR, Lemeshow S, Saulnier F. A new Simplified Acute Physiology Score (SAPS II) based on a European/North American multicenter study. JAMA. 1993;270(24):2957-63. PMID 8254858.


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Updated Nov 10, 2018
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