IMPACT Score for Outcomes in Head Injury

Probability of 6-month mortality or unfavorable outcome = 1 / (1 + e -x ), where x is as follows: Model 6-month outcome Mortality Unfavorable outcome* Core x = -3.109 + addition of the selected points** x = -2.644 + addition of the selected points Extended x = -3.787 + addition of the selected points x = -3.023 + addition of the selected points Lab x = -3.184 + addition of the selected points x = -2.470 + addition of the selected points *Unfavorable outcome = death, persistent vegetative state, or severe disability. **Points for each variable in the core, extended, and lab models are provided below. 1) Core model Variable Points for mortality Points for unfavorable outcome Age, years Age x 0.034 Age x 0.038 Motor score (if on sedation/paralysis or unable to be assessed, mark as "Not testable (NT)") Obeys commands (+6) 0 0 Localizes pain (+5) 0 0 Withdrawal from pain (+4) 0.390 0.632 Flexion to pain (+3) 0.797 1.266 Extension to pain (+2) 1.397 2.078 No motor response (+1) 1.447 1.393 Not testable (NT) 0.522 0.885 Pupils Both reactive 0 0 One reactive 0.514 0.592 Neither reactive 1.239 1.216 2) Extended model Variable Points for mortality Points for unfavorable outcome Age, years Age x 0.032 Age x 0.033 Motor score (if on sedation/paralysis or unable to be assessed, mark as "Not testable (NT)") Obeys commands (+6) 0 0 Localizes pain (+5) 0 0 Withdrawal from pain (+4) 0.313 0.575 Flexion to pain (+3) 0.746 1.185 Extension to pain (+2) 1.207 1.852 No motor response (+1) 1.205 1.218 Not testable (NT) 0.425 0.837 Pupils Both reactive 0 0 One reactive 0.334 0.442 Neither reactive 0.970 1.003 Marshall CT classification* Diffuse injury I -0.298 -0.530 Diffuse injury II 0 0 Diffuse injury III or IV (swelling or shift) 0.774 0.543 V or VI (evacuated or non-evacuated mass lesion) 0.651 0.497 Traumatic subarachnoid hemorrhage on CT No 0 0 Yes 0.606 0.567 Epidural hematoma on CT No 0 0 Yes -0.379 -0.572 Hypoxia No 0 0 Yes (or suspected) 0.237 0.316 Hypotension No 0 0 Yes (or suspected) 0.667 0.614 3) Lab model Variable Points for mortality Points for unfavorable outcome Age, years Age x 0.020 Age x 0.029 Motor score (if on sedation/paralysis or unable to be assessed, mark as "Not testable (NT)") Obeys commands (+6) 0 0 Localizes pain (+5) 0 0 Withdrawal from pain (+4) 0.310 0.548 Flexion to pain (+3) 0.778 1.186 Extension to pain (+2) 1.109 1.801 No motor response (+1) 0.965 1.105 Not testable (NT) 0.462 0.059 Pupils Both reactive 0 0 One reactive 0.090 0.201 Neither reactive 0.533 0.712 Marshall CT classification* Diffuse injury I -0.150 -0.567 Diffuse injury II 0 0 Diffuse injury III or IV (swelling or shift) 0.715 0.508 V or VI (evacuated or non-evacuated mass lesion) 0.807 0.571 Traumatic subarachnoid hemorrhage on CT No 0 0 Yes 0.740 0.666 Epidural hematoma on CT No 0 0 Yes -0.510 -0.687 Hypoxia No 0 0 Yes (or suspected) 0.360 0.396 Hypotension No 0 0 Yes (or suspected) 0.366 0.440 Glucose, mmol/L Glu x 0.097 Glu x 0.085 Hemoglobin, g/dL Hgb x -0.086 Hgb x -0.092 *Marshall CT classification: Classification Definition Diffuse injury I No visible intracranial pathology Diffuse injury II Cisterns present, midline shift ≤5 mm and/or lesion densities, no high/mixed density lesion >25 cm³ Diffuse injury III Cisterns compressed or absent, midline shift ≤5 mm, no high/mixed density lesion >25 cm³ Diffuse injury IV Midline shift >5 mm, no high/mixed density lesion >25 cm³ V Any surgically-evacuated lesion VI High/mixed density lesion >25 cm³, not surgically evacuated