GFAp and tau protein as predictors of neurological outcome after out-of-hospital cardiac arrest: A post hoc analysis of the COMACARE trial

AIM: To determine the ability of serum glial fibrillary acidic protein (GFAp) and tau protein to predict neurological outcome after out-of-hospital cardiac arrest (OHCA). METHODS: We measured plasma concentrations of GFAp and tau of patients included in the previously published COMACARE trial (NCT02698917) on intensive care unit admission and at 24, 48, and 72 h after OHCA, and compared them to neuron specific enolase (NSE). NSE concentrations were determined already during the original trial. We defined unfavourable outcome as a cerebral performance category (CPC) score of 3–5 six months after OHCA. We determined the prognostic accuracy of GFAp and tau using the receiver operating characteristic curve and area under the curve (AUROC). RESULTS: Overall, 39/112 (35%) patients had unfavourable outcomes. Over time, both markers were evidently higher in the unfavourable outcome group (p < 0.001). At 48 h, the median (interquartile range) GFAp concentration was 1514 (886–4995) in the unfavourable versus 238 (135–463) pg/ml in the favourable outcome group (p < 0.001). The corresponding tau concentrations were 99.6 (14.5–352) and 3.0 (2.2–4.8) pg/ml (p < 0.001). AUROCs at 48 and 72 h were 0.91 (95% confidence interval 0.85–0.97) and 0.91 (0.85–0.96) for GFAp and 0.93 (0.86–0.99) and 0.95 (0.89–1.00) for tau. Corresponding AUROCs for NSE were 0.86 (0.79–0.94) and 0.90 (0.82–0.97). The difference between the prognostic accuracies of GFAp or tau and NSE were not statistically significant. CONCLUSIONS: At 48 and 72 h, serum both GFAp and tau demonstrated excellent accuracy in predicting outcomes after OHCA but were not superior to NSE. CLINICAL TRIAL REGISTRATION: NCT02698917 (https://www.clinicaltrials.gov/ct2/show/NCT02698917).