In the present study, we unfortunately performed an extensive literature review to examine the clinical usefulness of NSE and S-100B as post-resuscitation neurological prognostic predictors.To improve applicability of study results in clinical practice, we considered the following three points when designing the present study: a consistent definition of poor (good) outcome should be used in assessing data from multiple studies; the cut-off values for biochemical markers should be set so that specificity in prediction of poor outcome is 100%; and the time points of blood sampling should be fixed in assessing the time course of change in blood levels of biochemical markers. Although few reviews of application of biological markers to prediction of neurological outcome in CA after CPR published meet the above requirements [1,10], the present study is the first extensive literature review that does meet them.

Materials and methodsLiterature searchA Medline search of literature published before August 2008 was performed using the following search terms: ‘neuron-specific enolase and cardiac arrest’, ‘neuron-specific enolase and cardiopulmonary resuscitation’, ‘NSE and cardiac arrest’, and ‘NSE and cardiopulmonary resuscitation’ with respect to NSE, and ‘S100 and cardiac arrest’ and ‘S100 and cardiopulmonary resuscitation’ with respect to S-100B. Cross-references were retrieved from the studies and reviews thus identified. The search included all types of publications (reviews, original studies, case reports, and editorials), but excluded those not in English and animal experimental studies.

One author (KS) performed the selection and reviewed all full-text papers.Selection of studiesPublications examining the clinical usefulness of NSE or S-100B as a prognostic predictor in two outcome groups, ‘favorable outcome’ Drug_discovery and ‘poor outcome’, were reviewed, with case reports excluded at this stage. When a study examined a prognostic predictor (or predictors) other than NSE and S-100B as well, only the results for NSE and/or S-100B were reviewed.Definition of outcomeCerebral performance was evaluated according by Cerebral Performance Categories (CPC) 1 to 5 of the Glasgow-Pittsburgh Outcome Categories [11] and the Glasgow Outcome Scale [12,13] (GOS) scores 1 to 5, as recommended by the Utstein Template [4]. The relations between the corresponding grades in the two different grading systems were considered to be as follows. CPC 1 (‘good cerebral performance: conscious and alert with normal neurological function or only slight cerebral disability’) was equivalent to GOS 5 (‘good recovery: able to return to work or school’).