Elevated Serum Glial Fibrillary Acidic Protein (GFAP) is Associated with Poor Functional Outcome After Cardiopulmonary Resuscitation

Background The neurological prognosis of patients after cardiopulmonary resuscitation (CPR) is difficult to assess. GFAP is an astrocytic intermediate filament protein released into bloodstream in case of cell death. We performed a prospective study aiming to compare the predictive potential of GFAP after resuscitation to the more widely used biomarker neuron-specific enolase (NSE). Methods One hundred patients were included at 48 h (tolerance interval +/- 12 h) after cardiac arrest. A serum sample was collected immediately after study inclusion. We determined serum levels of GFAP and NSE by means of immunoassays. Primary outcome was the modified Glasgow outcome scale at 4 weeks. Values below four were considered as a poor functional outcome. Results Median GFAP levels in poor outcome (n = 61) and good outcome (n = 39) patients were 0.03 mu g/L (interquartile range 0.01-0.07 mu g/L) and 0.02 mu g/L (0.01-0.03 mu g/L; p = 0.014), respectively. GFAPrevealed a sensitivity of 60.7% and a specificity of 66.7% to predict a poor functional outcome. All patients having a GFAP level > 0.08 mu g/L had a poor functional outcome. For NSE, sensitivity was 44.3% and specificity was 100.0% for predicting a poor outcome. Multivariate regression analysis revealed GFAP, NSE, and the Karnofsky index to be independent predictors of outcome. Conclusions The release patterns of GFAP and NSE after CPR show differences. GFAP levels above 0.08 mu g/L were associated with a poor outcome in all cases, and patients with strongly elevated values (> 3 mu g/L) consistently had severe brain damage on brain imaging. Both biomarkers independently contribute to outcome prediction after CPR.