Background Social inequality in ischaemic heart disease has been related to socioeconomic position in childhood, early adulthood and late adulthood. However, the impact of relative level of accumulated income periods across adult life course and the potential gender and age differences have not been investigated. The aim was to investigate the association between relative level of accumulated income across the life course and acute myocardial infarction (AMI) from age 60+ years and to study if the associations differ by gender and in different age groups (30–39 years, 40–49 years and 50–59 years).
Methods All Danes born 1935–1954 (N=1 235 139) were followed up in registers for incident AMI (42 669 cases). The accumulated proportional deviation from median equivalised income (APDMEI) for each gender/age/calendar year strata was constructed and divided in quartiles. The associations were analysed by means of Cox’s proportional hazard models.
Results Among men, those in the lowest APDMEI quartile had an HR 1.40 (1.35–1.45) of AMI compared with the highest quartile. Those in the second and third highest quartiles had HR of 1.24 (1.20–1.28) and 1.14 (1.10–1.18), respectively. Among women, the lowest quartile had an HR of 1.78 (1.69–1.88), the second 1.45 (1.37–1.53) and the third 1.19 (1.13–1.26). The social gradient was similar across the different age groups.
Conclusion The risk of AMI increased with lower levels of relative accumulated income across the life course. While men generally had a higher risk of AMI, the social gradient was steeper in women. There was no indication of a specific sensitive age period for exposure to relative level of accumulated income.
- health inequalities
- life course epidemiology
- epidemiology of chronic non communicable diseases
- cardiovascular disease
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Contributors MK, CØH and RL generated the idea for the paper, and MK and CØH prepared an analytical plan and conducted all data analyses. IA, MK and RL drafted the introduction. MK drafted the methods, results and discussion sections. HB-H contributed to critical revision of the design and statistical analyses. CØH designed figure 1. All the authors contributed to the interpretation of the results and critical revision of the paper and approved the final version.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data cannot be made publicly available due to regulations. A SAS code for the project is available upon request from MK.
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