Relationship between socioeconomic status and stroke: An observational and network Mendelian randomization study

Abstract

Background

The relationship between socioeconomic status (SES) and stroke remains controversial, and the underlying mediator is unclear. This study aimed to assess the causal relationship of SES with stroke and its subtypes and to identify potential modifiable risk factors responsible for this relationship.

Methods

The study included 372,437 participants from the UK Biobank. Over an average period of 12.13 years, 6,457 individuals (2.7 %) were recorded as having experienced a stroke. Cox proportional hazards model was used to determine the relationship between SES (average annual household income before tax and age at the end of full-time education) and stroke, ischemic stroke, and hemorrhagic stroke. Two-sample Mendelian randomization (MR) was employed to assess the causal relationship between SES and stroke and its subtypes. Furthermore, network MR was utilized to evaluate the potential mediating role of modifiable risk factors for stroke in this causal relationship.

Results

After adjusting for factors such as sociodemographic characteristics, health behaviors, health status, and past medical history, participants in the second highest income group showed the lowest risk of stroke, with a hazard ratio (HR) of 0.780 (95 % confidence interval [CI]: 0.702–0.866), and for ischemic stroke, the HR was 0.701 (95 % CI: 0.618–0.795). Those who completed full-time education at the latest age group(>18 years) had the lowest risk of stroke (HR: 0.906, 95 % CI: 0.830–0.988) and ischemic stroke (HR: 0.897, 95% CI: 0.811–0.992). MR analysis showed that higher income and education were both associated with a lower risk of stroke (income: inverse-variance-weighted odds ratio [OR_IVW] =0.796, 95 % CI: 0.675–0.940, education: OR_IVW = 0.631, 95 % CI: 0.557–0.716) and ischemic stroke (income: OR_IVW = 0.813, 95 % CI: 0.684–0.966, education: OR_IVW = 0.641, 95 % CI: 0.559–0.735). Additionally, hypertension had the highest mediating effect on this relationship. It accounted for 57.12 % of the effect of income on stroke, 51.24 % on ischemic stroke, and 27 % and 24 % for education.

Conclusion

Higher SES was associated with a lower risk of stroke and ischemic stroke, and hypertension had the highest mediating effect on this causal relationship. The results have significant public health implications, emphasizing the importance of early intervention to reduce the risk of stroke in low SES populations.