Socioeconomic inequalities in cardiovascular disease: a causal perspective

Socioeconomic inequalities in cardiovascular disease (CVD) persist in high-income countries despite marked overall declines in CVD-related morbidity and mortality. After decades of research, the field has struggled to unequivocally answer a crucial question: is the association between low socioeconomic position (SEP) and the development of CVD causal? We review relevant evidence from various study designs and disciplinary perspectives. Traditional observational, family-based and Mendelian randomization studies support the widely accepted view that low SEP causally influences CVD. However, results from quasi-experimental and experimental studies are both limited and equivocal. While more experimental and quasi-experimental studies are needed to aid causal understanding and inform policy, high-quality descriptive studies are also required to document inequalities, investigate their contextual dependence and consider SEP throughout the lifespan; no simple hierarchy of evidence exists for an exposure as complex as SEP. The COVID-19 pandemic illustrates the context-dependent nature of CVD inequalities, with the generation of potentially new causal pathways linking SEP and CVD. The linked goals of understanding the causal nature of SEP and CVD associations, their contextual dependence, and their remediation by policy interventions necessitate a detailed understanding of society, its change over time and the phenotypes of CVD. Interdisciplinary research is therefore key to advancing both causal understanding and policy translation. Low socioeconomic position (SEP) is associated with an increased risk of cardiovascular disease (CVD), but whether this association is causal is uncertain. In this Review, Bann and colleagues discuss how evidence from divergent study designs can help in understanding the causal relationship between SEP and CVD and how this relationship might have been affected by the COVID-19 pandemic. Socioeconomic disparities in cardiovascular disease (CVD) remain an important public health challenge; however, the causal nature of this association remains elusive.Understanding causality is crucial for the generation of robust evidence and to inform policy.Evidence from traditional observational, family-based and Mendelian randomization studies supports the generally well-accepted view that low socioeconomic position (SEP) causally influences CVD.Results from quasi-experimental and experimental studies are mixed and often null, with few available studies; more evidence is required to improve causal understanding and inform policy.No simple hierarchy of evidence exists for an exposure as complex as SEP; each study design has value, and a need remains both for more evidence across each study design and for studies that triangulate across multiple designs.High-quality descriptive studies remain valuable to document associations and examine their contextual dependence; for example, the COVID-19 pandemic might have altered causal processes linking SEP and CVD.

Automated summary

Socioeconomic inequalities in cardiovascular disease persist despite overall declines in morbidity and mortality. The causality between low socioeconomic position (SEP) and CVD is still uncertain. Traditional observational, family-based, and Mendelian randomization studies support the causal influence of low SEP on CVD, while quasi-experimental and experimental studies have mixed and limited results. More research is needed to understand the causal relationship and inform policy.