SAPS II
Calculate SAPS II score for ICU mortality risk using 15 variables including vitals, labs, GCS, and comorbidities. Free SAPS II calculator with score breakdown and mortality prediction.
About This Calculator
About the SAPS II Calculator
The SAPS II (Simplified Acute Physiology Score II) Calculator is a severity-of-disease classification system designed for patients aged 15 years and older admitted to Intensive Care Units (ICUs). Developed by Le Gall and colleagues in 1993 from a multicenter database of 12,997 patients across 12 countries, SAPS II helps clinicians assess the severity of critical illness and predict in-hospital mortality risk.
The SAPS II score is calculated using the worst physiological values recorded within the first 24 hours of ICU admission across 12 physiological variables and 3 disease-related variables. Each variable is assigned points based on predefined thresholds, with total scores ranging from 0 to 163 points. The total score is then transformed into a predicted mortality probability using a logistic regression equation: logit = -7.7631 + 0.0737 × score + 0.9971 × ln(score + 1), with mortality = exp(logit) / (1 + exp(logit)).
Physiological variables include age, heart rate, systolic blood pressure, temperature, Glasgow Coma Scale, PaO₂/FiO₂ ratio (for mechanically ventilated patients), urine output, serum BUN, serum sodium, serum potassium, serum bicarbonate, serum bilirubin, and white blood cell count. Disease-related variables include metastatic cancer, hematologic malignancy, AIDS, and type of admission (scheduled surgical, medical, or unscheduled surgical).
Regional Notes
India: SAPS II is widely used in Indian ICUs for severity scoring and benchmarking across both public and private hospital settings. It complements the APACHE II and SOFA scoring systems commonly employed in Indian critical care practice.
United States: SAPS II is used alongside APACHE IV and MPM0-III in US ICUs. Many US hospitals report standardized mortality ratios (SMR) using SAPS II for quality improvement and ICU performance benchmarking.
United Kingdom: The UK's Intensive Care National Audit and Research Centre (ICNARC) has developed its own risk prediction model, though SAPS II remains in use for research and international comparisons. UK ICUs often use SAPS II alongside ICNARC for case-mix adjustment.
Important: This calculator is for educational and reference purposes only. It is not a substitute for professional medical judgment. Always consult a qualified healthcare professional for clinical decision-making.
Frequently Asked Questions
What is SAPS II score?
The Simplified Acute Physiology Score II (SAPS II) is a severity-of-disease classification system for ICU patients aged 15 or older. It uses 12 physiological measurements and 3 disease-related variables to compute a score from 0 to 163, which is then converted to an estimated hospital mortality probability.
How is SAPS II different from APACHE II?
SAPS II uses 15 variables (12 physiological + 3 disease-related) compared to APACHE II's 17 variables, and does not require a chronic health evaluation as detailed as APACHE II's. SAPS II was developed from a larger multicenter database (12,997 patients across 12 countries) and requires only the worst values in the first 24 hours of ICU admission.
What is a normal SAPS II score?
SAPS II scores range from 0 to 163. Lower scores indicate lower severity. A score of 10 corresponds to approximately 1-2% predicted mortality, 25 points to about 10% mortality, 52 points to 50% mortality, and 77 points to about 90% mortality. The relationship between score and mortality follows a sigmoidal curve.
When should SAPS II be calculated?
SAPS II is calculated using the worst physiological values within the first 24 hours of ICU admission. It should be calculated once per ICU stay. If the patient is discharged and readmitted to the ICU, a new SAPS II can be calculated. It is not intended for patients with burn injuries or those admitted after cardiac surgery.
How is SAPS II mortality calculated?
The predicted hospital mortality is calculated using the formula: logit = -7.7631 + 0.0737 × score + 0.9971 × ln(score + 1). Mortality probability = exp(logit) / (1 + exp(logit)). The formula was derived from logistic regression analysis of 12,997 ICU patients in the original 1993 study by Le Gall et al.
Which variables are included in SAPS II?
SAPS II includes 12 physiological variables: age, heart rate, systolic blood pressure, temperature, Glasgow Coma Scale, PaO2/FiO2 ratio (if ventilated), urine output, serum urea or BUN, sodium, potassium, bicarbonate, bilirubin, and white blood cell count. It also includes 3 disease-related variables: metastatic cancer, hematologic malignancy, AIDS, and type of admission (scheduled surgical, medical, unscheduled surgical).