Elsevier

Resuscitation

Volume 157, December 2020, Pages 49-59
Resuscitation

Review
Association of measures of socioeconomic position with survival following out-of-hospital cardiac arrest: A systematic review

https://doi.org/10.1016/j.resuscitation.2020.09.025Get rights and content

Abstract

Background

Survival following out-of-hospital cardiac arrest (OHCA) is low, and poor survival appears associated with low socioeconomic position (SEP). We aimed to synthesise the evidence regarding association of specific SEP measures with OHCA survival, as well as effect modification and potential mediators, with the goal of informing efforts to improve survival by highlighting characteristics of populations requiring additional resources, and identifying modifiable factors.

Methods

MEDLINE and Embase databases were searched on 23 May 2019. Quantitative primary studies considering the association of any SEP measure with any OHCA survival measure were eligible. SEP could be measured at the level of the patient, their residential area, or OHCA location. Data on study characteristics and outcomes were extracted and a narrative review performed; this considered the evidence for overall SEP-survival association, variation in association of different SEP measures with survival, effect modification, and mediation.

Results

Twenty-three studies were included. These were highly heterogeneous, particularly regarding SEP measures and eligibility criteria. Several studies report a SEP-survival association, with this being almost exclusively in the direction of lower survival with lower SEP. There is some indication that the education-survival association is particularly consistent but further work is needed to increase confidence here. No evidence of effect modification by age, sex or other factors was seen, although few studies considered this. No mediators were conclusively identified.

Conclusions

Low SEP is associated with poorer OHCA survival in at least some settings. It may be appropriate to consider populations’ socioeconomic characteristics when targeting interventions to improve OHCA survival.

Introduction

Cardiac arrest refers to sudden halting of cardiac mechanical activity, indicated by absence of signs of circulation.1 This may have a cardiac cause such as myocardial infarction, or non-cardiac cause such as drug overdose or airway obstruction.2 Out-of-hospital cardiac arrest (OHCA) is a particular healthcare challenge due to the need for rapid action and co-ordination of bystanders, emergency medical services (EMS), and hospital.3 The proportion of patients that survive OHCA varies between countries, but is generally low; a multicentre European study reported survival to hospital discharge in only 8% of patients who received cardiopulmonary resuscitation (CPR) (0–18% inter-country range).4

Work to understand predictors of OHCA survival may identify factors that could be targeted to improve survival, or highlight characteristics of populations with poor survival where interventions could be focused. Socioeconomic factors are one characteristic of interest. A recent systematic review found a generally consistent pattern of decreased OHCA survival in patients of lower socioeconomic position (SEP), such as 70% improved odds of 30-day survival in the most highly educated quintile relative to least,5 although several studies observed no such SEP-OHCA survival association.6 This was in addition to higher OHCA incidence in low SEP areas.6

Understanding which SEP measures, such as education or income, best identify likelihood of poor OHCA survival may help elucidate SEP-survival causal pathways and further guide targeting of interventions to subpopulations. Understanding whether the SEP-OHCA survival relationship differs by factors such as age and sex (effect modification) may also be informative here. While the previous review found insufficient evidence to draw conclusions around either of these aspects,6 we identified several additional relevant papers and therefore aimed to consider both aspects in more detail. We also considered the evidence for potential factors mediating any SEP-survival relationship, aiming to identify further potentially modifiable factors.

While population characteristics such as race and ethnicity may also be related to SEP in some settings, this is likely to vary significantly between countries. As we intended to review the global literature, we focused on economic factors such as education and income, considering these to be of broadest relevance.

Section snippets

Eligibility criteria

Eligibility criteria are detailed in Table 1. Briefly, primary studies considering the association of any SEP measure with any OHCA survival measure were eligible.

Study selection

MEDLINE and Embase databases were searched via Ovid using comprehensive search strategies (see supplementary materials), on 23 May 2019. All records were transferred into EndNote, duplicates removed, and initially screened by title or abstract to remove those clearly ineligible according to the Table 1 criteria. Full texts of

Results

The database searches yielded 3642 unique records, with 20 meeting the eligibility criteria. Reviewing their references yielded three more records. Fig. 1 outlines the number of records at each stage.

SEP-survival association

In almost all of the included studies, any association observed between a SEP measure and OHCA survival was in the direction of low SEP with decreased survival. The two exceptions are one study reporting an association of increased property value with decreased survival,11 and one reporting possible decreased survival in an intermediate income level relative to no income, but no association when comparing the most extreme categories.7 Though notably, several studies found no evidence of an

Conclusions

The current literature is generally supportive of any association of SEP with OHCA survival being in the direction of decreased survival with lower SEP, although an association is not seen in all studies. This further supports the need to reduce socioeconomic deprivation in society. It also suggests it may be appropriate to consider socioeconomic characteristics of populations when targeting CPR training and other resources to improve survival, especially given evidence of lower SEP being

Conflicts of interest

None.

Authors’ contribution

RC: Conceptualisation, Methodology, Data Curation, Analysis, Writing – Original Draft, Writing – Review & Editing. CB: Validation, Writing – Review & Editing. GC: Conceptualisation, Writing – Review & Editing. NH: Conceptualisation, Methodology, Writing – Review & Editing, Supervision.

Acknowledgement

Dr Halbesma is supported by a British Heart Foundation Intermediate Basic Science Research Fellowship (FS/16/36/32205).

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