High Serum Soluble Fas Ligand Levels in Non-survivor Traumatic Brain Injury Patients.

Abstract

Soluble Fas Ligand (sFasL) is one of the main ligands that activates the apoptosis extrinsic pathway. Higher expression of FasL in brain samples and higher cerebrospinal fluid FasL concentrations in traumatic brain injury (TBI) patients than in controls have been found. However, the potential association between blood sFasL concentrations and TBI mortality has not been reported. Therefore, the objective of this study was to determine whether that association exists. We included patients with a severe isolated TBI, defined as < 9 points in Glasgow Coma Scale (GCS) and < 10 non-cranial aspects points in Injury Severity Score in this observational and prospective study performed in 5 Intensive Care Units. We measured serum sFasL concentrations on day 1 of TBI. We found that 30-day survivor (n = 59) in comparison to non-survivor patients (n = 24) had higher GCS (p = 0.001), lower age (p = 0.004), lower APACHE-II score (p < 0.001), lower intracranial pressure (ICP) (p = 0.01), lower computer tomography (CT) findings of high risk of death (p = 0.02) and lower serum sFasL concentrations (p < 0.001). The area under the curve for mortality prediction by serum sFasL levels was of 75% (95% CI = 63%-87%; p < 0.001). In Kaplan-Meier analysis was found that patients with serum sFasL levels > 29.2pg/mL had a higher mortality rate (Hazard ratio = 6.2; 95% CI = 2.6-14.8; p < 0.001). Multiple logistic regression analysis found an association between serum sFasL levels and mortality after controlling for GCS, age and CT findings (OR = 1.055; 95% CI = 1.018-1.094; p = 0.004), and after controlling for APACHE-II, ICP and CT findings (OR = 1.048; 95% CI = 1.017-1.080; p = 0.002). The association between serum sFasL levels and 30-day mortality in TBI patients was the major novel finding of our study; however, future validation could be interesting to confirm those results.