Review articleCognitive impairments in survivors of out-of-hospital cardiac arrest: A systematic review☆
Introduction
During a cardiac arrest the brain can suffer from a temporary limitation in blood supply, which can lead to hypoxic brain injury. One of the main clinical consequences of hypoxic brain injury is cognitive impairment. Although cognitive impairments may not be directly visible, they can affect a person's life greatly in daily activities, in participation in society and in quality of life.1, 2, 3 It is currently unclear how often cognitive impairments occur after a cardiac arrest, and what kind of cognitive problems occur most frequently. Existing publications, dedicated to cognitive function after cardiac arrest, vary in study design, research population and outcome measures used. Some studies report that the incidence of neurological sequelae is remarkably low,4, 5 while others state that survivors of out-of-hospital cardiac arrest are seriously disabled because of their neuropsychological deficits.6, 7 To our knowledge, evidence on this topic has not yet been reviewed systematically. The aim of this study is to review systematically current evidence on the frequency and nature of cognitive impairments in survivors of out-of-hospital cardiac arrest.
Section snippets
Methods
A systematic literature search was performed using the databases Pubmed, Embase, PsychInfo and Cinahl. Details on the search strategies are presented in Appendix 1. The literature search was performed by the first reviewer (VM) in March 2007. The publications for this review were selected based on the inclusion criteria as described in Table 1.
Two independent reviewers (VM + JV) selected eligible articles (see Fig. 1 for flowchart of the selection process). If the two reviewers disagreed and
Results
The initial literature search resulted in 286 titles, extracted from the four databases. Further selection based on title, abstract and full text, resulted in a final selection of 28 articles (see Fig. 1). In Table 2, the inter-observer agreement in the different stages of the selection process can be found.
Discussion
This systematic review revealed only a few high quality studies on the nature and frequency of long-term cognitive impairments after out-of-hospital cardiac arrest. After critically reviewing all selected articles, only three relatively large (n = 45, 57 and 58), qualitatively sound, prospective studies remained in which cognition was measured with a battery of neuropsychological tests.10, 12, 14 The results suggest that cognitive impairments are common after out-of-hospital cardiac arrest and
Ethical approval
Ethical approval was not required.
Contributions
V. Moulaert was the first reviewer, performed the literature search and is the guarantor of this study. J. Verbunt acted as second reviewer. Both reviewers read all the selected titles and abstracts and selected the final articles for the review. C. van Heugten was the third reviewer and acted as a mediator in case of disagreement between the two reviewers and then made the final decision. All authors participated in the selection of a quality criteria scoring list and contributed to the
Funding
The study was funded by the Netherlands Organisation for Health Research and Development (ZON/MW) and Fonds Nuts/Ohra.
Conflict of interest
The authors declare that they have no competing interests.
Acknowledgements
We would like to thank Jill Hayden for providing us with the original version of her quality criteria list. We kindly acknowledge Daniel Keszthelyi and Ward Vanagt for their help in translating the Hungarian and French articles, respectively.
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A Spanish translated version of the summary of this article appears as Appendix in the final online version at doi:10.1016/j.resuscitation.2008.10.034.