Let I(condition) equal 1 when the condition is present and 0 otherwise. Use systolic blood pressure (SBP) and PaO₂ in mm Hg, absolute base excess in mmol/L, and FiO₂ as a fraction.

Component	Contribution to PIM3 logit
Both pupils >3 mm and fixed	`3.8233 × I(condition)`
Elective ICU admission	`−0.5378 × I(condition)`
Mechanical ventilation in the first hour	`0.9763 × I(condition)`
Absolute base excess	`0.0671 × \|base excess\|`
SBP linear term	`−0.0431 × SBP`
SBP quadratic term	`0.0001716 × SBP²`
Oxygenation term	`42.14 × FiO₂ / PaO₂`
Recovery from cardiac surgery with bypass	`−1.2246`
Recovery from cardiac procedure without bypass	`−0.8762`
Recovery from non-cardiac surgery or procedure	`−1.5164`
Very high-risk diagnosis	`1.6225`
High-risk diagnosis	`1.0725`
Low-risk diagnosis	`−2.1766`
Intercept	`−1.7928`

Recovery or diagnosis categories not listed in the table contribute 0.

PIM3 logit = sum of all contributions

Predicted mortality risk (%) = 100 × exp(logit) / [1 + exp(logit)]

Paediatric Index of Mortality 3 (PIM3)