Prospective evaluation of a predictive model of mortality in patients with isolated head injury

Towards development of a survival prediction tool for pediatric head injury

BACKGROUND

The ability to provide an accurate prognosis for children with traumatic brain injury (TBI) would be useful for the children's families and the caregivers. In this study we examined whether an appropriate mathematical model can predict survival in this patient population.

METHODS

Data from the Children's Hospital of Eastern Ontario (CHEO) TBI registry was analyzed. First, a series of univariate logistic regressions was performed to ascertain the significance of individual predictors, such as age, maximum Glasgow Coma Scale (GCS) score, maximum head injury Abbreviated Injury Scores (AIS) and the Injury Severity Score (ISS). Second, a multinomial logistic regression was fitted using only individually significant predictors and inmodel predictor significance, and interactions were tested. Only two significant predictors were kept in the final model. This final model was subsequently used to predict survival for each individual patient using the n-1 training set (i.e. Lachenbruch's leave-one-out method). The receiver operating characteristics (ROC) method was used to ascertain specificity-sensitivity trade-offs at different probability cut-offs in order to predict survival.

RESULTS

Only the maximum GCS and head injury AIS remained significant, both individually and in the polynomial logistic regression. Empiric ROC curve analyses from leave-one-out survival predictions showed statistical significance (area under the curve = 0.87, Z = 6.8, p < 0.001). Only 12% of cases were misclassified using the 'best' cut-off.

CONCLUSION

An outcome predictive model for pediatric TBI can be devised using an appropriate mathematical model. It may help to estimate expected outcomes in pediatric TBI more objectively.

Pre-hospital hypothermia is not associated with increased survival after traumatic brain injury

BACKGROUND

Conclusions from in vivo and in vitro studies suggest hypothermia may be protective in traumatic brain injury (TBI). Few studies evaluated the effect of admission temperature on outcomes. The purpose of this study is to examine the relationship between admission hypothermia and mortality in patients with isolated, blunt, moderate to severe TBI.

METHODS

The Los Angeles Trauma Database was queried for all patients ≥ 14 y of age with isolated, blunt, moderate to severe TBI (head abbreviated injury score (AIS) ≥ 3, all other <3), admitted between 2005 and 2009. The study population was then stratified into two groups by admission temperature: hypothermic (≤ 35°C) and normothermic (>35°C). Demographic characteristics and outcomes were compared between groups. Logistic regression analysis was used to determine the relationship between admission hypothermia and mortality.

RESULTS

A total of 1834 patients were analyzed and then stratified into two groups: hypothermic (n = 44) and normothermic (n = 1790). There was a significant difference noted in overall mortality (25% versus 7%), with the hypothermic group being four times more likely to succumb to their injuries. After adjusting for confounding factors, admission hypothermia was independently associated with increased mortality (AOR 2.5; 95% CI 1.1-6.3; P = 0.04).

CONCLUSIONS

Although in-vivo and in-vitro studies demonstrate induced hypothermia may be protective in TBI, our study demonstrates that admission hypothermia was associated with increased mortality in isolated, blunt, moderate to severe TBI. Further prospective research is needed to elucidate the role of thermoregulation in patients sustaining TBI.