S. S. Cai2, B. W. Bonds1, D. M. Stein1 1University Of Maryland,R Adams Cowley Shock Trauma Center,Baltimore, MD, USA 2University Of Maryland,School Of Medicine,Baltimore, MD, USA
Introduction: Recent studies reported elevated cardiac troponin I (cTnI) was frequently observed following severe traumatic brain injury (TBI) and was associated with poor outcomes. Exact relationship is not well understood and the clinical applicability of cTnI in severe TBI patients has yet to be determined. Present study investigated the relationship between cTnI levels and risk of mortality.
Methods: Adult patients (≥ 18y) with severe TBI (brain Abbreviated Injury Scale [AIS] score ≥ 3) admitted to a level one trauma center from July 2007 to January 2014 were reviewed. Patients with non-isolated severe TBI (AIS ≥ 3 to other anatomic regions) and those without cTnI measurements in 24 hours of admission were excluded. Four cTnI strata were predefined as undetectable (< 0.06 ng/mL) and detectable tertiles (0.06-0.1 ng/mL, 0.1-0.25 ng/mL, and > 0.25 ng/mL). Kaplan-Meier survival analysis and Cox proportional hazard model were applied. Stratification analysis was performed by age (≤ 65y or > 65y) and admission Glasgow Coma Scale (GCS) score (mild 13-15, moderate 9-12, and severe 3-8).
Results: In a total of 2711 patients, elevated cTnI was found in 502 (18.5%) patients. Five-day survival rate was significantly lower in the patients with detectable cTnI compared to those with undetectable cTnI (72.26% vs 88.77%, p < 0.0001). Risk of mortality increased with increasing cTnI levels in a dose-dependent manner (p-trend < 0.0001). Patient in the highest cTnI strata reported 1.55-fold (95% CI: 1.18-2.04, p-trend = 0.0002) higher hazard ratio (HR), or risk of mortality, compared with patients of undetectable cTnI when age, injury type, and injury severity were adjusted. Further stratification underscored the positive association between cTnI levels and risk of mortality, particularly in patients ≤ 65y (HR: 3.10, 95% CI: 2.09-4.59, p-trend < 0.0001) or with severe admission GCS (HR: 1.57, 95% CI: 1.16-2.14, p-trend = 0.0006). Similar association was not observed in patients > 65y or with mild or moderate admission GCS (Table 1).
Conclusion: Elevated cTnI is an independent predictor of mortality following severe TBI and is significantly associated with higher risk of mortality via a positive, non-linear dose-dependent relationship. This association is predominately seen in patients ≤ 65y or with severe admission GCS. Elevated cTnI may not be a useful predictor of mortality in patients > 65y or with mild or moderate admission GCS.
