Serum neuron-specific enolase as early predictor of outcome after in-hospital cardiac arrest: a cohort study

INTRODUCTION Outcome after cardiac arrest is mostly determined by the degree of hypoxic brain damage. Patients recovering from cardiopulmonary resuscitation are at great risk of subsequent death or severe neurological damage, including persistent vegetative state. The early definition of prognosis for these patients has ethical and economic implications. The main purpose of this study was to investigate the prognostic value of serum neuron-specific enolase (NSE) in predicting outcomes in patients early after in-hospital cardiac arrest. METHODS Forty-five patients resuscitated from in-hospital cardiac arrest were prospectively studied from June 2003 to January 2005. Blood samples were collected, at any time between 12 and 36 hours after the arrest, for NSE measurement. Outcome was evaluated 6 months later with the Glasgow outcome scale (GOS). Patients were divided into two groups: group 1 (unfavorable outcome) included GOS 1 and 2 patients; group 2 (favorable outcome) included GOS 3, 4 and 5 patients. The Mann-Whitney U test, Student's t test and Fisher's exact test were used to compare the groups. RESULTS The Glasgow coma scale scores were 6.1 +/- 3 in group 1 and 12.1 +/- 3 in group 2 (means +/- SD; p < 0.001). The mean time to NSE sampling was 20.2 +/- 8.3 hours in group 1 and 28.4 +/- 8.7 hours in group 2 (p = 0.013). Two patients were excluded from the analysis because of sample hemolysis. At 6 months, favorable outcome was observed in nine patients (19.6%). Thirty patients (69.8%) died and four (9.3%) remained in a persistent vegetative state. The 34 patients (81.4%) in group 1 had significantly higher NSE levels (median 44.24 ng/ml, range 8.1 to 370) than those in group 2 (25.26 ng/ml, range 9.28 to 55.41; p = 0.034). CONCLUSION Early determination of serum NSE levels is a valuable ancillary method for assessing outcome after in-hospital cardiac arrest.