APACHE IV Score Calculator

APACHE-IV: Purpose, limitations, and clinical context APACHE-IV (Acute Physiology and Chronic Health Evaluation, version IV) is an updated severity-of-illness model developed from a very large multi-center ICU cohort to estimate hospital mortality and length of stay for critically ill adults. The original publication describes a multivariable logistic procedure using first-24-hour physiologic data, age, chronic health items, admission diagnoses, and disease-specific coefficients and spline transformations to generate a raw score and predicted probabilities. APACHE-IV has excellent discrimination in the original validation cohort but is complex and may require periodic recalibration for different hospitals or patient populations.

This tool converts an existing APACHE-IV raw score into an estimated hospital mortality probability using a published logistic calibration frequently used in validation studies (logit = −3.347 + 0.029 × APACHE-IV score). That approach is suitable for benchmarking and retrospective risk estimation when the raw score is available. However, reproducing APACHE-IV from individual physiologic items (the original item-level algorithm and disease-specific adjustments) requires the full model details in the original publication and/or supplemental tables and, in some implementations, licensed code.

For highest fidelity and for automated generation from EHR data, use a licensed APACHE-IV implementation or obtain the model appendices and coefficients from the original paper's supplemental material and adapt them to your local dataset.