ReviewSocioeconomic inequalities in access to treatment for coronary heart disease: A systematic review☆,☆☆
Introduction
Cardiovascular disease morbidity and mortality are strongly associated with socioeconomic status (SES) [1], [2], [3]. Patients with low SES show higher morbidity, which is attributable to the increased prevalence of cardiac risk factors among these patients. Such risk factors include hypertension, cigarette smoking, obesity, and diabetes [4]. Therefore, patients with low SES have a greater need for medical services. SES-related differences in coronary heart disease (CHD) mortality are related not only to cardiac risk factors but also to unequal access to treatment [5], [6]. Guidelines have been developed to standardize treatment and thereby reduce mortality by providing a comprehensive overview of current evidence-based recommendations. CHD treatment includes both non-invasive and invasive cardiac procedures, such as coronary angiography (CAG) and revascularization (percutaneous coronary intervention, PCI; coronary artery bypass grafting, CABG), pharmacological treatment, and rehabilitation. The guidelines state that treatment should be equally provided to all patients according to their health status and needs [7], [8], [9], [10]. In addition, universal healthcare systems provide, at least in theory, access to treatment that is independent of SES [11].
Although most healthcare systems are organized in a fairly equitable manner, international studies have indicated that patients with CHD have unequal access to treatment [5], [12], [13]. However, many of these studies were performed before the implementation of guidelines, in an era when, for example, PCI was not the gold standard for the treatment of acute myocardial infarction (AMI). To the best of our knowledge, only one review has reported on the relationship between socioeconomic inequalities and treatment access among patients with CHD. Quatromoni and Jones [14] focused on studies from the USA and the UK and measured treatment access according to waiting times for and availability of invasive cardiac procedures. They found that patients with low SES waited longer and experienced reduced rates of CAG, PCI and CABG. Additionally, few reviews have analyzed the predictors of access to cardiac rehabilitation (CR) for patients with CHD, and those showed that income and education are associated with referral and participation, to the disadvantage of patients with low SES [15], [16], [17]. Access to and utilization of healthcare cannot be clearly differentiated in the majority of international studies. Access to healthcare is a characteristic predominantly based on care-provider availability and healthcare system design and is determined by supply and demand. In contrast, utilization of healthcare is a characteristic predominantly based on patient preferences and choices [18], [19]. For example, when measuring rates of dispensed drugs using register data, it remains unclear whether patients lacking dispensed drugs received no prescription/had no access to drugs or whether they simply did not utilize their access to drugs by not filling an issued prescription. Therefore, when using the term “access” in this review, we are not indicating whether the barrier is associated with the system or the patient.
The relationship between access to CHD treatment and SES across different countries is unclear, especially since treatment has been standardized through guidelines, and it is unknown at what stage (e.g., diagnosis, revascularization, or secondary prevention) the relationship is most pronounced. Furthermore, it is not known how the relationship between SES and access to treatment differs when using different measures of SES and in the context of different types of healthcare systems. Therefore, the current study aimed to summarize the existing evidence on the relationship between socioeconomic inequality and access to treatment for CHD.
Section snippets
Methods
To perform this review, we searched the electronic databases Medline and Web of Science to identify studies in medicine, sociology and economics that were published in either English or German. The search was limited to articles published from 1996 through 2015, as the treatment of CHD and its complications changed after the implementation of standardized guidelines in 1996 [9].
Different combinations of the following keywords were used for the search: coronary heart disease, ischemic heart
Results
Altogether, 2066 different publications were eligible for further screening. Of these, 1972 articles were excluded based on their titles and abstracts. After screening the full texts of the remaining 94 articles, another 37 articles were excluded based on our eligibility criteria. Finally, 57 articles were included in this systematic review (Fig. 1).
The 57 included studies used a wide variety of methodological approaches. Furthermore, several different aspects of CHD treatment were analyzed in
Discussion
The present review is among the first to analyze the relationship between SES and access to treatment for patients with CHD. The findings cover several factors of treatment, from non-invasive and invasive coronary procedures to secondary prevention measures (such as rehabilitation or drug treatment), reflecting the complex treatment that must be used to manage a chronic disease. The findings suggest that patients with low SES are affected by socioeconomic inequalities to their disadvantage,
Conclusion
Our findings show that clear socioeconomic differences exist in access to treatment for CHD. For patients with low SES, reduced treatment access was predominately found for invasive procedures, especially diagnostic procedures such as CAG. This relationship was less pronounced for secondary prevention measures, such as medication and CR. Overall, these relationships suggest that there is a potential risk for underdiagnosed CHD in a group of patients (i.e., those with low SES) who are at high
Author contributions
Sara L Schröder, Matthias Richter, Jochen Schröder, Stefan Frantz, Astrid Fink.
All authors jointly defined the research question and search strategy and jointly discussed the information extraction. SLS and AF performed the literature search and discussed the risk of bias assessment. SLS conducted the information extraction, assessed the risk of bias and drafted the manuscript. All authors helped draft the manuscript and approved the final version.
Conflict of interest
The authors report no relationship that could be construed as a conflict of interest.
Acknowledgements
We thank Niels Bormann (NB) for assistance with the risk of bias assessment of the studies reported in this review.
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All authors takes responsibility for all aspects of the reliability and freedom from bias of the data presented and their discussed interpretation.
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This work was supported by the Wilhelm Roux Programme of the Medical Faculty of Martin Luther University, Halle-Wittenberg (grant number FKZ: 28/40).