Neuroprognostication of cardiac arrest patients remains a challenge. We evaluated the early prognostic value and optimal time of measuring serum and cerebrospinal fluid (CSF) tau protein levels to predict neurologic outcome in postcardiac arrest patients treated with targeted temperature management (TTM). We also evaluated the cutoff values in predicting poor outcomes. Patients treated with TTM following cardiac arrest, from May 2018 to June 2019, were included in the study. Serum and CSF tau levels were obtained and compared immediately, at 24, 48, and 72 hours after return of spontaneous circulation (ROSC). The area under the receiver-operating characteristic curve (AUROC) and the Delong method were used to identify the cutoff values of serum and CSF tau protein levels in predicting poor outcomes at each interval. Of 38 patients enrolled, 16 experienced poor outcomes. Both serum and CSF tau levels were consistently higher in the poor outcome group than in the good outcome group. The AUROCs of serum and CSF tau protein were not significantly different at each time point. Immediately after ROSC, sensitivities of both serum and CSF tau protein levels were 31.25% at 100% specificity and increased to 86.6% and 73.3%, respectively, at 72 hours. This study demonstrates that serum and CSF tau protein levels could be used as valuable predictors of neurologic outcomes in postcardiac arrest patients treated with TTM. The early optimal time for measuring the serum and CSF tau protein levels was determined to be 72 hours after ROSC.
Keywords: cardiac arrest; cerebrospinal fluid; prognostication; tau protein.