Elsevier

Australian Critical Care

Volume 28, Issue 4, November 2015, Pages 196-202
Australian Critical Care

Research paper
Gender difference in treatment and mortality of patients with ST-segment elevation myocardial infarction admitted to Victorian public hospitals: A retrospective database study

https://doi.org/10.1016/j.aucc.2015.01.004Get rights and content

Abstract

Background

Death from acute coronary syndrome (ACS) is avoidable with early reperfusion therapy, however, evidence suggests inequity in women's ACS treatment within a number of international healthcare systems, when compared to men's. Research indicates mortality rates are higher in some age groups of women when compared to men for the sub-group of ACS known as ST-segment elevation myocardial infarction (STEMI).

Objective

To determine whether patient sex was associated with patterns of reperfusion treatment variation or increased inhospital mortality in patients with STEMI.

Methods

We undertook retrospective analyses on a government database for patients admitted to Victorian public hospitals with STEMI. Patients were categorised into two age groups: 18–64 and 65–84 years (inclusive), to determine whether patient sex and these age groups influenced treatment from 2005 to 2008 and mortality from 2005 to 2010.

Results

Both younger and older women received less frequent angioplasty with stent and more often received no reperfusion treatment than men in corresponding younger and older age groups (p = 0.006 and p < 0.001, respectively). Overall, women in both age groups were more likely to die inhospital than men from equivalent age groups with STEMI (p < 0.001, both groups).

Conclusions

Proportionately, both younger and older women received less interventional reperfusion therapy for STEMI than their male cohorts, and died more often during admission than men. Further research needs to be undertaken to verify the findings and causes, and guide future research to ensure application of evidence to treatment in patients with STEMI.

Introduction

Acute coronary syndrome (ACS) is a leading cause of morbidity and mortality worldwide, including in Australia.1, 2, 3 In many developed countries, mortality rates from ACS, which include acute myocardial infarction (AMI) and unstable angina, have fallen over recent decades,1, 4 but improvements have not been equitable between the sexes, with reports that women's ACS rates of death are either stabilising or increasing.5, 6, 7 Fewer women experience ACS, but depending on their age, they tend to have higher mortality rates.8, 9, 10 Women are more likely to have repeat ACS events than men, which are more often fatal than those experienced by men.11 First and subsequent ACS events are predicted to increase further in the next decade due to the ageing population,9, 11 making investigation of ACS of paramount importance.

ST-segment elevation myocardial infarction (STEMI) is a type of ACS acknowledged to be a cardiac emergency.12 It accounts for approximately one-quarter of all ACS events,12 and is more common in men.6 Comprehensive management of ACS using evidence-based guidelines is critical to patient outcome. This includes re-establishing patency of occluded coronary arteries with percutaneous coronary intervention (PCI) or fibrinolytic therapy early to enable reperfusion of affected myocardial cells to prevent permanent myocardial damage, which is associated with high rates of morbidity and death. Access to early reperfusion therapy has been found to reduce deaths from STEMI by up to 78%.13

White and Chew2 estimated that maximising numbers of patients treated with reperfusion therapy would save a further 270 lives per 10 000 patients with STEMI.2 They argued that although numerous novel treatment options continue to be developed, most future gains would come from implementing the therapies already available, properly.2

Two important studies investigating ACS in Australia and New Zealand over the last decade were the ACACIA Registry14, 15 and SNAPSHOT ACS Study.16 Through a number of reports arising from these studies, an issue identified as of critical significance for the future reduction of morbidity and mortality from ACS was access to treatment.13, 16 Other studies have reported 30–40% of patients did not receive reperfusion therapy to which they were eligible,17, 18 which was similar to under-treated proportions of STEMI populations reported in North America19 and Europe.20

Despite the consistency in ACS guidelines across the United States,21 Europe,22 and Australia and New Zealand,23, 24 knowledge translation into clinical practice is often suboptimal.2, 12, 13 Recent Australian reports concur that although knowledge of recommended ACS-care is high, implementation of guidelines is poor.13, 16 A number of international studies report figures of under-treatment related to patient sex which adversely affect women.25, 26, 27

Although ACS guidelines are ‘gender neutral’,5 differences in ACS management related to patient sex have been reported.25 Some overseas studies document disparities in the application of evidence-based treatment of STEMI in inpatient hospital settings due to patient sex,25, 26 but we were unable to ascertain if similar differences existed in Australia. We wanted to evaluate reperfusion therapy and mortality patterns for Victorian patients over several years for STEMI, comparing treatment access and inhospital mortality between the sexes.

The current study seeks to further this discussion with inhospital patient data to answer the following research questions:

  • 1.

    Is interventional reperfusion therapy equally provided to younger and older men and women patients admitted to Victorian public hospitals with STEMI?

  • 2.

    Are patterns of inhospital mortality different between younger and older men and women patients admitted to Victorian public hospitals with STEMI?

Section snippets

Methods

Retrospective analyses of the State Government, Department of Health (DoH) Victorian Admitted Episodes Dataset (VAED) for patients aged 18–85 years admitted to Victorian hospitals with the principal diagnosis of STEMI were conducted (n = 13 744). We compared reperfusion treatment patterns and mortality rates for men and women patients in both younger (<65 years) and older (≥65 years) age groups to enable comparison of patient age separately because of women's longer average life expectancy.28 Data

Patient demographic characteristics, 2005–2010

A total of 13 744 patient admissions for 18–85 year olds were recorded in 136 Victorian public hospitals with STEMI diagnoses for 5 years (July 1st, 2005 to June 30th, 2010). STEMIs of the inferior myocardial wall were most commonly diagnosed for both sexes (Table 1). There were more men than women in all groups (p < 0.001). The mean patient age was 61.8 (±12.7) years. Overall, women (n = 3501; 25.5%) were older than men (n = 10 243; 74.5%) by more than six years [66.6 (±12.9) vs. 60.2 (±12.3) years

Discussion

The principal findings of this exploratory database study were that, in comparison to men; proportionately fewer women received reperfusion treatment for STEMI, and women experienced higher rates of inhospital mortality for STEMI. Additionally, average lengths of stay in some inpatient areas differed significantly between the sexes. We investigated average lengths of stay for patients aged younger and older than 65 years, and found younger women stayed longer in coronary care units (CCU), but

Conclusion

This research has provided evidence of possible disparity in reperfusion treatment access for STEMI between men and women in a populous Australian state. Although the findings need to be corroborated with further research, the current paper's findings indicate a difference in care which may be unfair and avoidable, but most importantly, may result in avoidable death. The research provides evidence of possible practice gaps in the management of patients with STEMI which can be further defined,

Authors’ contributions

LK, KP, MAR and LWC conceived and designed the study. LK conducted the literature review. LK, KP and LWC collected the data. LK and KP analysed the data. LK prepared the manuscript. LK, KP, MAR and LWC critically revised and edited the manuscript draft prior to submission and approved the final manuscript. LK, KP, MAR and LWC revised the manuscript for resubmission.

Acknowledgements

Lisa Kuhn was supported by an Australian Postgraduate Award with Stipend and a grant from the Royal College of Nursing, Australia National Research and Scholarship Fund. The authors would like to thank Brooke MacPherson, formerly Data Analysis staff at the Victorian Department of Health (DoH) and her colleagues for working with Lisa to extract the necessary data from the DoH administered dataset.

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