SAPS II Score Calculator

What Is the Simplified Acute Physiology Score II (SAPS II)?

The Simplified Acute Physiology Score II (SAPS II) is a globally recognized severity-of-illness classification and mortality prediction system for adult intensive care unit (ICU) patients. Developed by Le Gall et al. in 1993 from a large international multicenter cohort, SAPS II converts 12 physiological variables, age, admission type, and underlying chronic disease status during the first 24 hours of ICU admission into a calibrated point score ranging from 0 to 163.

SAPS II Mortality Prediction Equation

The predicted risk of hospital death is derived using the standard logistic regression model:

$$\text{Logit} = -7.7631 + 0.0737 \times (\text{SAPS II}) + 0.9971 \times \ln(\text{SAPS II} + 1)$$

$$\text{Probability of In-Hospital Death } (P) = \frac{e^{\text{Logit}}}{1 + e^{\text{Logit}}} \times 100\%$$

SAPS II Parameter Categories and Points

Data must reflect the worst value recorded during the first 24 hours of ICU admission:

• Demographics: Age (< 40 yrs: 0 pts, up to $\ge 80$ yrs: 18 pts).
• Vital Signs: Heart rate, systolic blood pressure, core body temperature.
• Neurological: Glasgow Coma Scale (GCS 14–15: 0 pts, GCS < 6: 26 pts).
• Respiratory: $\text{PaO}_2 / \text{FiO}_2$ ratio (scored only if on mechanical ventilation or CPAP).
• Renal & Electrolytes: 24-hour urine output, blood urea nitrogen (BUN) or serum urea, serum potassium, sodium, and bicarbonate.
• Hepatic & Hematologic: Total bilirubin, white blood cell count (WBC).
• Admission & Chronic Disease: Scheduled surgical (0 pts) vs. medical (6 pts) vs. unscheduled surgical (8 pts); chronic comorbid conditions including metastatic cancer, hematologic malignancy, and AIDS.

Clinical Uses and Benchmarking

SAPS II is widely used for:

• Benchmarking ICU performance and quality of care against international standardized mortality ratios (SMR).
• Stratifying disease severity in clinical trials and intensive care research.
• Assessing physiological compromise alongside scores like the Revised Trauma Score Calculator and RSBI Calculator.