Table 2.
Univariate/bivariate logistic regression analysis for IMPACT core and physiologic variables
| Variable | A/D AUC (95% CI) | p value | F/U AUC (95% CI) | p value |
|---|---|---|---|---|
| Age | 0.737 (0.652–0.737) | < 0.0001 | 0.680 (0.605–0.754) | < 0.0001 |
| Admission GCS Motor | 0.559 (0.409–0.612) | 0.160 | 0.576 (0.497–0.655) | 0.022 |
| Admission Pupil Reactivity | 0.440 (0.336–0.524) | 0.196 | 0.440 (0.372–0.507) | 0.228 |
| Mean ICP | 0.642 (0.538–0.746) | < 0.0001 | 0.495 (0.413–0.577) | 0.059 |
| Mean AMP | 0.671 (0.567–0.775) | < 0.0001 | 0.527 (0.445–0.609) | 0.045 |
| Mean RAP* | 0.669 (0.575–0.762) | 0.002 | 0.659 (0.582–0.735) | 0.0007 |
| Mean RAP AUC Above 0 | 0.619 (0.526–0.712) | 0.015 | 0.495 (0.413–0.576) | 0.359 |
| Mean RAP AUC above + 0.4 | 0.635 (0.544–0.727) | 0.007 | 0.539 (0.458–0.620) | 0.137 |
| wICP | 0.712 (0.615–0.810) | 0.0002 | 0.627 (0.548–0.705) | 0.015 |
| Multi-variable models | ||||
| ICP + RAP AUC Above 0 | 0.618 (0.525–0.711) | < 0.0001 | 0.495 (0.414–0.577) | 0.126 |
| ICP + RAP AUC above + 0.4 | 0.633 (0.541–0.724) | < 0.0001 | 0.538 (0.457–0.619) | 0.069 |
| ICP + AMP | 0.657 (0.553–0.760) | 0.007 | 0.508 (0.426–0.590) | 0.222 |
| ICP + AMP + mean RAP | 0.653 (0.548–0.758) | 0.0001 | 0.503 (0.421–0.586) | 0.001 |
Italicized p values are those reaching significance (i.e., p < 0.05). *Despite these mean values of RAP demonstrate significant associations with the dichotomized outcomes, they are difficult to interpret given the nature of RAP. RAP values near 0 can mean both good and poor compensatory reserve, as such, during the averaging process to produce mean values over a recording period, it becomes difficult to interpret the meaning of such measures
AMP pulse amplitude of ICP, A/D alive/dead, AUC area under the receiver operating curve, CI confidence interval, F/U favorable/unfavorable outcome (i.e., favorable = Glasgow Outcome Scale of 5 to 8; unfavorable = Glasgow Outcome Scale of 1 to 4), ICP intra-cranial pressure, IMPACT International Mission for Prognosis and Analysis of Clinical Trials, RAP compensatory reserve index (moving correlation between AMP and ICP), RAP AUC integrated area under the RAP curve over time, wICP compensatory-reserve-weighted ICP (wICP = (1 − RAP) × ICP)