Distinct predictive values of current neuroprognostic guidelines in post-cardiac arrest patients

Purpose: To assess the performance of neuroprognostic guidelines proposed by the American Academy of Neurology (AAN), European Resuscitation Council/European Society of Intensive Care Medicine (ERC/ESICM), and American Heart Association (AHA) in predicting outcomes of patients who remain unconscious after cardiac arrest. Methods: We retrospectively identified a cohort of unconscious post-cardiac arrest patients at a single tertiary care centre from 2011 to 2017 and reviewed hospital records for clinical, radiographic, electrophysiologic, and biochemical findings. Outcomes at discharge and 6 months post-arrest were abstracted and dichotomized as good (Cerebral Performance Category (CPC) scores of 1-2) versus poor (CPC 3-5). Outcomes predicted by current guidelines were compared to actual outcomes, with false positive rate (FPR) used as a measure of predictive value. Results: Of 226 patients, 36% survived to discharge, including 24 with good outcomes; 52% had withdrawal of life-sustaining therapies (WLST) during hospitalization. The AAN guideline yielded discharge and 6-month FPR of 8% and 15%, respectively. In contrast, the ERC/ESICM had a FPR of 0% at both discharge and 6 months. The AHA predictors had variable specificities, with diffuse hypoxic-ischaemic injury on MRI performing especially poorly (FPR 12%) at both discharge and 6 months. Conclusions: Though each guideline had components that performed well, only the ERC/ESICM guideline yielded a 0% FPR. Amongst the AAN and AHA guidelines, false positives emerged more readily at 6 months, reflective of continuing recovery after discharge, even in a cohort inevitably biased by WLST. Further assessment of predictive modalities is needed to improve neuroprognostic accuracy.