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Traumatic Brain Injury (IMPACT)

Death and unfavourable outcome six months after moderate or severe traumatic brain injury, from admission characteristics.
IMPACT, Steyerberg et al. 2008.

6-Month Mortality
Unfavourable Outcome at 6 Months

Many patients, or checking your outcomes? Use a spreadsheet.

Complete the required fields. Each optional section adds a larger model.

Age years

Best motor response (GCS motor)

Pupillary reactivity

Hypoxia before or at admission

Hypotension before or at admission

Marshall CT classification

Traumatic subarachnoid haemorrhage

Epidural haematoma

Glucose at admission

3 to 20 mmol/L or 54 to 360 mg/dL

Haemoglobin at admission

6 to 17 g/dL, 60 to 170 g/L or 3 to 10 mmol/L

Predicted Outcomes

Each outcome shows one estimate per model whose fields are filled.

6-Month Mortality

Probability of death within 6 months of injury.

Unfavourable Outcome at 6 Months

Probability of death, vegetative state or severe disability (Glasgow Outcome Scale 1–3) at 6 months after injury.

Methodology

Research use only. The IMPACT models were developed on 8,509 patients with moderate or severe traumatic brain injury from 11 studies, and validated externally on 6,681 patients from the CRASH trial. The authors note that the predictions are “a bit too pessimistic for current patients”. Not a substitute for clinical judgement.

Structured Input

Three admission fields give the Core estimate. Adding CT findings and secondary insults gives Core + CT; adding glucose and haemoglobin as well gives Core + CT + Lab.

Published Model

Three logistic regression models per outcome, from the IMPACT group's published coefficients.

Probability

Each model returns a probability, shown as a whole-number percentage. There are no risk bands.

Known Limits

The estimates use admission data only and do not account for treatment after admission.

Model & Cohort

This page hosts the IMPACT prognostic models published by Steyerberg et al. in 2008, with the permission of the IMPACT investigators. The IMPACT group is developing an updated model; this page will move to it when it is published.

8,509

Development cohort

Development studies

6,681

External validation cohort (CRASH)

Validation Design

In the CRASH trial, the Core model's AUC was 0.776 for 6-month mortality and 0.780 for unfavourable outcome; the Core + CT model's was 0.801 and 0.796. The Lab model has not been validated externally. Across the development studies, AUCs ranged from 0.66 to 0.84. In CRASH, outcomes were worse than predicted overall (Hosmer-Lemeshow p < 0.001) and close to predicted in high-income countries. The published coefficients are rounded, so estimates here can differ from the IMPACT website by up to 1 percentage point.

Authors

Andrew I.R. Maas

Principal Investigator

Antwerp University Hospital, Belgium

Ewout W. Steyerberg

Lead Investigator

Professor of Clinical Biostatistics, UMC Utrecht & LUMC Leiden

Gordon D. Murray

Lead Investigator

University of Edinburgh, United Kingdom

Anthony Marmarou

Lead Investigator 2003–2010

Virginia Commonwealth University, Richmond, USA

Contact & Citation

Contact: questions about the model: tbi-impact.org. Questions about this page: our Contact page.

Citation: Steyerberg EW, Mushkudiani N, Perel P, et al. Predicting outcome after traumatic brain injury: development and international validation of prognostic scores based on admission characteristics. PLoS Med 2008;5(8):e165. doi:10.1371/journal.pmed.0050165

Coefficients: Coefs_model_fit_2006_v2.pdf, from the IMPACT website.

Version

v0.1.3 · models@da1572a