Elsevier

Resuscitation

Volume 82, Issue 11, November 2011, Pages 1399-1404
Resuscitation

Clinical paper
An early, novel illness severity score to predict outcome after cardiac arrest

https://doi.org/10.1016/j.resuscitation.2011.06.024Get rights and content

Abstract

Background

Illness severity scores are commonly employed in critically ill patients to predict outcome. To date, prior scores for post-cardiac arrest patients rely on some event-related data. We developed an early, novel post-arrest illness severity score to predict survival, good outcome and development of multiple organ failure (MOF) after cardiac arrest.

Methods

Retrospective review of data from adults treated after in-hospital or out-of-hospital cardiac arrest in a single tertiary care facility between 1/1/2005 and 12/31/2009. In addition to clinical data, initial illness severity was measured using serial organ function assessment (SOFA) scores and full outline of unresponsiveness (FOUR) scores at hospital or intensive care unit arrival. Outcomes were hospital mortality, good outcome (discharge to home or rehabilitation) and development of multiple organ failure (MOF). Single-variable logistic regression followed by Chi-squared automatic interaction detector (CHAID) was used to determine predictors of outcome. Stepwise multivariate logistic regression was used to determine the independent association between predictors and each outcome. The Hosmer–Lemeshow test was used to evaluate goodness of fit. The n-fold method was used to cross-validate each CHAID analysis and the difference between the misclassification risk estimates was used to determine model fit.

Results

Complete data from 457/495 (92%) subjects identified distinct categories of illness severity using combined FOUR motor and brainstem subscales, and combined SOFA cardiovascular and respiratory subscales: I. Awake; II. Moderate coma without cardiorespiratory failure; III. Moderate coma with cardiorespiratory failure; and IV. Severe coma. Survival was independently associated with category (I: OR 58.65; 95% CI 27.78, 123.82; II: OR 14.60; 95% CI 7.34, 29.02; III: OR 10.58; 95% CI 4.86, 23.00). Category was also similarly associated with good outcome and development of MOF. The proportion of subjects in each category changed over time.

Conclusions

Initial illness severity explains much of the variation in cardiac arrest outcome. This model provides prognostic information at hospital arrival and may be used to stratify patients in future studies.

Introduction

The treatment of a patient with restoration of spontaneous circulation (ROSC) after cardiac arrest has evolved significantly. In particular, the syndrome of post-cardiac arrest illness has been described as consisting of several distinct, pathophysiological changes.1 Severity of illness is an important determinant of the response to therapeutic interventions. Classifying post-cardiac arrest patients with historical features, such as initial cardiac rhythm, or event-related features, such as witnessed collapse or location of collapse, is a surrogate for the physiological state of the patient. These classifications suffer from modest reliability2 and weak association with in-hospital clinical course.3 While several illness severity scores have been developed for critically ill patients, prior scores for post-cardiac arrest patients rely on some event-related data.4, 5 Data obtained after ROSC and prior to reaching target temperature were used to stratify post-cardiac arrest patients into clinically meaningful illness severity categories. Such categories permit tailoring of therapy for post-arrest patients. Rates of survival, neurologic outcome and development of multiple organ failure (MOF) are presented for each category.

Section snippets

Methods

This study was approved by the University of Pittsburgh Institutional Review Board. Subjects did not provide written informed consent for this study as these data are part of an ongoing quality assurance/quality improvement initiative in our facility.

Results

Of 495 subjects treated during this time period, 457 had valid data for analysis. Excluded subjects (N = 38) more frequently experienced IHCA, were comatose, and were treated in 2008 (corresponding to a loss of data during the change in electronic medical record systems for the ICU; p < 0.05). Excluded subjects less frequently experienced a primary rhythm of VF/VT, received TH, and received coronary angiography (p < 0.05) (Table 1).

The proportion of comatose subjects in categories II and III

Discussion

This study identified four distinct categories of post-cardiac arrest illness severity based on neurological dysfunction combined with cardiopulmonary dysfunction during the first few hours after ROSC. Survival, good outcome, and MOF varied greatly between categories, and the proportions of patients in different categories varied over time. The present results emphasize that illness severity should be carefully measured and accounted for in future studies of therapies.

The category of early

Conclusions

Initial illness severity explains much of the variation in cardiac arrest outcomes. This model provides prognostic information at hospital arrival and a universal nomenclature to stratify patients in future studies.

Conflicts of interest statement

The authors have no relevant conflicts of interest to report.

Acknowledgements

JCR and this project are supported by Grant Number 1 KL2 RR024154 from the National Center for Research Resources. The content is solely the responsibility of the authors and do not necessarily represent the official views of the NCRR or the National Institutes of Health. JCR is also supported by an unrestricted grant from the National Association of EMS Physicians/Zoll EMS Resuscitation Research Fellowship.

The authors also would like to acknowledge Dr. Garrick Kwok for his assistance in chart

References (25)

  • W.A. Knaus et al.

    APACHE – acute physiology and chronic health evaluation: a physiologically based classification system

    Crit Care Med

    (1981)
  • E.F. Wijdicks et al.

    Validation of a new coma scale: the FOUR score

    Ann Neurol

    (2005)
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    A Spanish translated version of the abstract of this article appears as Appendix in the final online version at doi:10.1016/j.resuscitation.2011.06.024.

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