http://www.tbi-impact.org/?p=impact/calc
see also CRASH.
Based on extensive prognostic analysis the IMPACT investigators have developed prognostic models for predicting 6 month outcome in adult patients with moderate to severe head injury (Glasgow Coma Scale ⇐12) on admission. By entering the characteristics into the calculator, the models will provide an estimate of the expected outcome at 6 months. They presented three models of increasing complexity (Core, Core + CT, Core + CT + Lab). These models were developed and validated in collaboration with the CRASH trial collaborators on large numbers of individual patient data (the IMPACT database). The models discriminate well, and are particularly suited for purposes of classification and characterization of large cohorts of patients. Extreme caution is required when applying the estimated prognosis to individual patients.
Letsinger et al. conducted an anonymous international, multidisciplinary survey of practitioners who provide care to patients with traumatic brain injury. Questions were designed to determine current use rates of the IMPACT prognostic calculator and thresholds of age and risk for death or poor outcome that might cause practitioners to consider withholding aggressive care. Correlations between physician aggressiveness, putative predictors of aggressiveness, and demographics were examined. One hundred fifty-four responses were received, half of which were from physicians who were familiar with the IMPACT calculator. The most frequent use of the calculator was to improve communication with patients and their families. On average, respondents indicated that in patients older than 76 years or those with a >85% chance of death or poor outcome it might be reasonable to pursue non-aggressive care. These thresholds were robust and were not influenced by provider or institutional characteristics. This study demonstrates the need to educate physicians about the IMPACT prognostic calculator. The consensus values for age and prognosis identified in our study may be explored in future studies aimed at reducing variability in physician aggressiveness and should not serve as a basis for withdrawing care 1).
For Wan et al. the IMPACT prognosis calculator showed just fair discrimination when predicting the outcome of the elderly patients with severe TBI. Management decisions should be made on a case-by-case basis rather than by relying on the predicted risks identified by this model; conservative treatment might be preferable when expected risk of fatal outcome is >90% 2).
In a university hospital in Colombia, the Marshall CT score, IMPACT, and Corticosteroid Randomization After Significant Head Injury models overestimated the adverse neurologic outcome in patients with severe head trauma 3).
A study evaluated the usefulness of the IMPACT prognostic calculator (IPC) for patients receiving acute neurointensive care at a level 1 trauma center in Germany. A total of 139 patients with traumatic brain injury (TBI) were assessed. One day after trauma, the extended model of the IPC was found to provide the most valid prediction of 6-month mortality/unfavorable outcome. Different time frames within the first day could be determined by analyzing mild, moderate, and severe TBI cohorts. The CORE + CT model at time frame Z2 (<6 h from the point of first documentation) for mild TBI exhibited the highest values in the receiver operating characteristic (ROC) analysis (area under the curve [AUC], 0.9; sensitivity, 1; specificity, 0.7). For patients with moderate head injury at time frame Z2/3 (<6-12 h from point of first documentation), the extended model fit best. For patients with severe TBI, the extended model at time frame Z6 (48-72 h from point of first documentation) best predicted 6-month mortality and unfavorable outcome (ROC analysis: AUC, 0.542/0.445; sensitivity, 0.167/0.364; specificity, 0.575/0.444). Center-specific validation demonstrated the validity of the IPC in the early phase after TBI. These findings support the usefulness of the IPC for predicting the prognosis of patients with TBI. However, further prospective validation using a larger TBI cohort is needed 4).