Modeling serum level of s100β and bispectral index to predict outcome after cardiac arrest

Objectives This study was designed to evaluate multimodal prognostication in patients after cardiac arrest (CA). Background Accurate methods to predict outcome after CA are lacking. Methods Seventy-five patients with CA treated with therapeutic hypothermia after cardiac resuscitation were enrolled in this prospective observational study. Serum levels of neuron-specific enolase (NSE) and neuron-enriched S100 beta (S100β) were measured 48 h after CA. Bispectral index (BIS) was continuously monitored during the first 48 h after CA. The primary endpoint was neurological outcome, as defined by the cerebral performance category (CPC) at 6-month follow-up: scores 1 or 2 indicated good outcome, and scores 3 to 5, poor outcome. The secondary endpoint was survival. Results A total of 46 (61%) patients survived at 6 months and 41 (55%) patients had CPC 1 or 2. Levels of NSE and S100β were higher in patients with poor outcomes compared with patients with good outcomes (4-fold and 10-fold, respectively; p < 0.001). BIS was lower in patients with poor outcomes (10-fold; p < 0.001). NSE, S100β, or BIS alone predicted neurological outcome, with areas under the receiver-operating characteristic curve (AUC) above 0.80. Combined determination of S100β and BIS had an incremental predictive value (AUC: 0.95). S100β improved discriminations based on BIS (p = 0.0008), and BIS improved discriminations based on S100β (p < 10^-5). Patients with S100β level above 0.03 μg/l and BIS below 5.5 had a 3.6-fold higher risk of poor neurological outcome (p < 0.0001). S100β and BIS predicted 6-month mortality (log-rank statistic: 50.41; p < 0.001). Conclusions Combined determination of serum level of S100β and BIS monitoring accurately predicts outcome after CA.