I.e. 31 of all cardiac arrest patients). CCT was generally ordered by treating physicians if the cause of the cardiac arrest was deemed uncertain or if intracranial complications were suspected. Our results should therefore be extended to the entire cardiac arrest population with care and corroboration by a prospective study avoiding selection bias is desirable. The same caveat applies to the comparison of different prognostic parameters, which could only be performed in the subset of patients who had received NSE, SSEP and CCT. The results of NSE, SEP and CCT were available Staurosporine PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/17139194 to the treating physicians and influenced decisions on limitation of treatment. Therefore, we cannot exclude the possibility of a self-fulfilling prophecy. GWR was calculated for this study and not known to treating physicians. However, reduced GWR reflects brain edema and treatment decisions were influenced by CT if brain edema was reported by the radiologist. As a number of recent studies have indicated limitedScheel et al. Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine 2013, 21:23 http://www.sjtrem.com/content/21/1/Page 7 ofreliability of prognostic parameters in hypothermia patients, treatment withdrawal within the first days after cardiac arrest is restricted to patients with confirmed brain death at our institution. In the remainder, treatment is continued up to day seven [19]. Hence, a major effect of a self-fulfilling prophecy from treatment withdrawal within the first days after cardiac arrest is unlikely in our study. Nonetheless, unexpected late recovery may occur in individual patients [5], and we cannot fully rule out that treatment withdrawal based on over-interpretation of prognostic parameters has prevented the detection of such exceptional cases.Conclusion Our study confirms the strong association of a low GWR with poor outcome. The optimal cut-off value of GWR was 1.16 in our study, which predicted poor outcome with 100 specificity and 38 sensitivity in our cohort of hypothermia treated patients. Most patients with GWR < 1.16 had absent SSEP or NSE > 97 g/L. Hence, GWR did not substantially increase the sensitivity to predict poor outcome if these two parameters were available. However, GWR may be useful in a multiparameter approach and may increase the certainty with which poor outcome can be predicted early after cardiac arrest in patients treated with hypothermia. Further prospective studies are needed to corroborate GWR thresholds and to evaluate the optimal timing of CCT for outcome prediction in cardiac arrest survivors. Additional fileAdditional file 1: Figure S1. ROC analysis for different GWR calculation methods. Competing interests All authors declare no conflict of interests. Authors’ contributions MS carried out the ROI measurements and statistical analysis and drafted the manuscript. CS designed the study, coordinated the collection of the data of the patients and drafted the manuscript. AG carried out the ROI measurements, participated in the statistical analysis and revised the manuscript. JN + FL collected the data of the patients and revised the manuscript. CP gave conceptual advice and revised the manuscript. CL designed the study, reviewed SSEPs and drafted the manuscript. All authors read and approved the final manuscript. Acknowledgments M. Scheel is supported by the Friedrich C. Luft Clinical Scientist Pilot Program funded by Volkswagen Foundation and Charit?Foundation. Author details 1 Department of N.