Abstract Details

Title Evaluating the Performance of the IMPACT Model in the Prehospital TXA for TBI Trial

Topic Neuro Trauma and Critical Care

Presentation(s) P14 - Poster Session 14 (11:45 AM-12:45 PM)

Poster/Presentation
Number 1-001

Objective To test the IMPACT model’s performance in a contemporary clinical trial population.

Background The International Mission on Prognosis and Analysis of Clinical Trials in Traumatic Brain Injury (IMPACT) prognostic model predicts functional outcome after moderate-severe traumatic brain injury (TBI). Our previous work suggested that glial fibrillary acidic protein (GFAP) may improve the discrimination of outcome when added to prognostic models.

Design/Methods

We analyzed data from a subset subjects from the phase II double-blind, multicenter randomized controlled trial, “Prehospital Tranexamic Acid Use for Traumatic Brain Injury.” This subset was limited to subjects in the placebo arm of the parent trial with evidence of hemorrhage on initial head computed tomographic (CT) scan. All 3 versions (core, extended, lab) of the IMPACT model were evaluated against 6-month mortality, plus an exploratory 4^th version (lab+GFAP). We compared our results to previously published validation results from the CENTER-TBI cohort.

Results Within the subset (n=166), 127 subjects had complete 6-month outcome data. Predictor variables were missing <10% (0-9.4%) of cases, and were imputed (GCS motor score, pupillary reactivity, serum glucose, serum hemoglobin, hypoxia, and Marshall CT score). GFAP was associated with mortality (p=0.004). The core model discriminated poorly in the subset (AUC 0.60 [95% CI: 0.48-0.71], p=0.096). The extended model discriminated well (AUC 0.73 [95% CI: 0.64-0.82], p<0.001). The lab model discriminated non-significantly better (AUC 0.76 [95% CI: 0.66-0.86], p=0.167). Adding GFAP to the lab model improved discrimination further (AUC 0.83 [95% CI: 0.76-0.90], p=0.004). All 4 models overestimated mortality compared with the observed rate (n=31, 24% v. 26-82%).

Conclusions In comparison with the observational CENTER-TBI validation cohort, the IMPACT models (core/extended/lab) discriminated mortality less well in a subset of the TXA trial. The addition of GFAP improved discrimination for mortality, but further work is needed to optimize its addition to the lab model.

Authors/Disclosures
H. E. Hinson, MD, MCR, FAAN (UCSF/Zuckerberg San Francisco General Hospital) PRESENTER	Dr. Hinson has received personal compensation in the range of $5,000-$9,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Neurology. Dr. Hinson has received personal compensation in the range of $5,000-$9,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for American Heart Association.
Shannon McWeeney	No disclosure on file
Adam Ferguson	The institution of Adam Ferguson has received research support from NIH. The institution of Adam Ferguson has received research support from VA. The institution of Adam Ferguson has received research support from DoD. The institution of Adam Ferguson has received research support from Wings for Life Foundation. The institution of Adam Ferguson has received research support from Craig H Neilsen Foundation. Adam Ferguson has received intellectual property interests from a discovery or technology relating to health care.
	No disclosure on file
Susan Rowell, MD, MCR	Dr. Rowell has nothing to disclose.

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