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

Abstract

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 μg/L (interquartile range 0.01-0.07 μg/L) and 0.02 μg/L (0.01-0.03 μg/L; p = 0.014), respectively. GFAP revealed 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 µg/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 µg/L were associated with a poor outcome in all cases, and patients with strongly elevated values (>3 µg/L) consistently had severe brain damage on brain imaging. Both biomarkers independently contribute to outcome prediction after CPR.

Keywords: Biomarker; Cardiac arrest; GFAP; NSE; Outcome.