CTD-ICU Infection-Related Acute Brain Dysfunction Risk Calculator

MIMIC-IV development cohort (n = 617) | 10-variable parsimonious logistic model

Research & validation note: This calculator is intended for research demonstration and as an adjunct to clinical decision-making; it has not been validated in a prospective cohort. External validation (eICU-CRD, n = 110) indicated that an intercept recalibration of −1.23 is required. If the target population's event prevalence differs substantially from MIMIC-IV, local recalibration is recommended before use.

Peak blood urea nitrogen, BUN (mg/dL) Maximum within first 24 h of ICU admission

Nadir serum calcium (mg/dL) Minimum within first 24 h of ICU admission

Peak temperature ≥ 38.0 °C

Yes No

Nadir temperature < 36.0 °C

Yes No

Neutrophil-to-lymphocyte ratio, NLR Enter absolute ratio; values < 0.1 are floored to 0.1

Mean arterial pressure, MAP (mmHg) Mean within first 24 h of ICU admission

Respiratory rate (breaths/min) Mean within first 24 h of ICU admission

Vasopressor use within 24 h

Yes No

Norepinephrine, epinephrine, dopamine, vasopressin, etc.

Nadir white blood cell count (K/µL) Minimum within first 24 h of ICU admission

24-hour urine output (mL) Enter whole mL (e.g. 1650); decimals lose precision

Model equation (raw scale, copy-ready)

logit(p) = 1.6493 + 0.0106 × BUN_max − 0.3400 × Calcium_min + 0.8743 × Fever38 − 0.7124 × Hypothermia + 0.3239 × log(NLR) − 0.0157 × MAP_mean + 0.0685 × RespRate_mean + 0.5342 × Vasopressor24h + 0.0258 × WBC_min − 0.0001 × UrineOutput24h p = exp(logit) / (1 + exp(logit))

Variable definitions & units

Variable	Definition	Unit / note
BUN_max	Peak blood urea nitrogen	mg/dL, first 24 h of ICU
Calcium_min	Nadir serum calcium	mg/dL, first 24 h of ICU
Fever38	Fever	Peak temperature ≥ 38.0 °C = 1, else 0
Hypothermia	Hypothermia	Nadir temperature < 36.0 °C = 1, else 0
NLR	Neutrophil/lymphocyte ratio	Natural log entered; <0.1 floored to 0.1
MAP_mean	Mean arterial pressure	mmHg, first 24 h of ICU
RespRate_mean	Respiratory rate	breaths/min, first 24 h of ICU
Vasopressor24h	Vasopressor use	Used within 24 h of ICU = 1, else 0
WBC_min	Nadir white blood cell count	K/µL, first 24 h of ICU
UrineOutput24h	24-hour urine output	mL

Risk stratification (used in this study)

Predicted probability	Stratum	Clinical interpretation
< 0.40	Low	Infection-related acute brain dysfunction unlikely; still evaluate non-infectious etiologies, with cultures and imaging as indicated.
0.40 – 0.60	Intermediate	Further differentiation required; re-assess dynamically while awaiting cultures.
≥ 0.60	High	Infection-related etiology likely; empirical antimicrobials and etiologic workup are likely beneficial.