Trajectories of daily inpatient blood biomarkers of physiological function improve mortality and morbidity prognostic model performance for patients with severe traumatic brain injury.

BACKGROUND

We sought to assess the prognostic value of incorporating daily inpatient physiological biomarker trajectories to the International Mission for Prognosis and Analysis of Clinical Trials in TBI (IMPACT) model for mortality and morbidity six months after severe traumatic brain injury (TBI).

METHODS

Patients with severe TBI (presenting Glasgow Coma Scale ≤ 8) were prospectively collected in a single-center database (n = 598). Morbidity (yes/no) was defined as Glasgow Outcome Scale Extended of 1-4. Daily blood labs (e.g., glucose, sodium, platelets, hemoglobin, neutrophils, lymphocytes, creatinine, blood urea nitrogen) were extracted for the first 14 days after injury. IMPACT was compared with IMPACT-extended (IMPACT + daily lab trajectories) for area under the curve (AUC). Net reclassification index (NRI) assessed the number of correctly reclassified cases for IMPACT-extended compared with IMPACT.

RESULTS

IMPACT-extended had a better AUC than IMPACT for mortality (AUC 0.93 vs. 0.84, P < 0.001) and morbidity (AUC 0.84 vs. 0.80, P < 0.001). NRI analyses revealed IMPACT-extended improved correct classifications of patients who survived to 6 months by 41%. NRI analyses revealed that IMPACT-extended modestly improved correct classification of controls by 4% compared with IMPACT.

CONCLUSIONS

Incorporating trajectories for daily blood biomarkers of physiological function significantly improves the discrimination and clinically relevant performance of existing prognostic models for both morbidity and mortality six months following severe TBI.