Neurofilament light chain for prognostication after cardiac arrest-first steps towards validation

Background: After cardiac arrest, many patients remain comatose, and a substantial proportion do not survive. Neuroprognostication is essential for identifying patients with potential for recovery, and those with severe, irreversible hypoxic-ischemic brain injury. Neurofilament light chain (NfL) is a blood-based marker of neuronal injury that is under evaluation for neuroprognostication. NfL have potential advantages over the currently only guideline recommended blood biomarker for neuroprognostication, neuron-specific enolase, including earlier applicability. However, there is no consensus on optimal NfL cut-off levels. A previous large investigation in OHCA patients, identified NfL thresholds with high specificity for poor outcome, and the purpose of the present investigation is to validate these cutoffs. Methods: The Blood Pressure and Oxygenation Targets in Post Resuscitation Care (BOX) trial included OHCA patients who were comatose at admission. Patients with at least one plasma biobank sample available at 24–48 h were included in this investigation. NfL was quantified by ELISA. Cerebral performance category score was estimated at 1 year. Diagnostic precision of NfL for prediction of poor neurologic outcome (CPC > 2) was determined by area under the receiver operator curve (AUROC), and the performance of previously identified cut-offs for a specificity of 100% were investigated. Results: A total of 638 patients had a NfL measurement at either 24 or 48 h. The AUROC for prediction of poor neurologic outcome was 0.95 and 0.95 at 24 and 48 h, respectively. At 24 h, a cut-off of 1232 pg/mL had a specificity of 98%, for prediction of poor neurologic outcome, and false-positive results for 7 patients (1.4%). At 48 h, a cut-off of 1539 pg/ml similarly had a specificity of 98%, and false-positive results for 7 patients (1.3%). Conclusions: The results of this investigation confirm the prognostic value of NfL for identification of risk of poor neurologic outcome after cardiac arrest. Previously identified cut-offs of 1232 pg/mL at 24 h, and 1539 pg/mL at 48 h, performed excellent with a very high specificity. This indicates that application of NfL will allow for reliable neuroprognostication as early as 24 h after cardiac arrest. Trial registration: ClinicalTrials.gov