Prediction of cognitive dysfunction after resuscitation from out-of-hospital cardiac arrest using serum neuron-specific enolase and protein S-100

Background: More than 50% of patients initially resuscitated from out-of-hospital cardiac arrest die in hospital. Objective: To investigate the prognostic value of serum protein S-100 and neuron-specific enolase (NSE) concentrations for predicting ( a) memory impairment at discharge; (b) in-hospital death, after resuscitation from out-of-hospital cardiac arrest. Methods: In a prospective study of 143 consecutive survivors of out-of-hospital cardiac arrest, serum samples were obtained within 12, 24-48 and 72-96 hours after the event. S-100 and NSE concentrations were measured. Pre-discharge cognitive assessment of patients (n = 49) was obtained by the Rivermead Behavioural Memory Test (RBMT). The relationship between biochemical brain marker concentrations and RBMT scores, and between marker concentrations and the risk of in-hospital death was examined. Results: A moderate negative relationship was found between S- 100 concentration and memory test score, at all time points. The relationship between NSE and memory test scores was weaker. An S- 100 concentration > 0.29 mu g/1 at time B predicted moderate to severe memory impairment with absolute specificity (42.8% sensitivity). S- 100 remained an independent predictor of memory function after adjustment for clinical variables and cardiac arrest timing indices. NSE and S- 100 concentrations were greater in patients who died than in those who survived, at all time points. Both NSE and S- 100 remained predictors of in-hospital death after adjustment for clinical variables and cardiac arrest timing indices. The threshold concentrations yielding 100% specificity for in-hospital death were S-100: 1.20 mu g/l ( sensitivity 44.8%); NSE 71.0 mu g/l ( sensitivity 14.0%). Conclusions: Estimation of serum S- 100 concentration after out-of-hospital cardiac arrest can be used to identify patients at risk of significant cognitive impairment at discharge. Serum S- 100 and NSE concentrations measured 24-48 hours after cardiac arrest provide useful additional information.