Diverging socioeconomic inequalities in all-cause and cardiovascular -specific mortality across generations: a comparative longitudinal analysis
F Chen, C Zhang, Z Liu, Q Li, C Danzeng, X Lang, Q Li, Y Zhu, D Wang, Y Zhao, B Hu, W LiAbstract
Background
Socioeconomic inequality is an essential driver of health disparities. Epidemiological evidence consistently links lower socioeconomic status (SES) to higher mortality, supporting its prioritization in health promotion strategies. Yet, how these inequalities evolve across successive generations in distinct national contexts and the potential factors that drives these disparities have not been fully elucidated.
Purpose
This study aims to compare generational trajectories of SES–mortality associations in the United States (US) and China, and identify underlying mechanisms to guide health policy.
Methods
We conducted a retrospective cohort study using two nationally representative datasets: US National Health and Nutrition Examination Survey 1999-2014 (n=19,383) and the China Health and Retirement Longitudinal Study (n=13,728). SES was derived via latent class analysis of education, income, and occupation, and categorized into three levels (Low SES, Middle SES and High SES). Participants were grouped into five generation cohorts (from pre-1930s to post-1960s). The primary outcome was all-cause mortality. Secondary outcome included cardiovascular (CV) mortality (for NHANES only). We estimated associations between SES and all-cause mortality using Cox proportional hazards models and relative index of inequality (RII). Confounders were fully adjusted, and sampling weights and competing-risk model were performed during NHANES analysis. We also applied Oaxaca-Blinder decomposition and mediation analyses to identify drivers of inequality.
Results
Overall, compared to high SES, low SES remained a risk factor for both all-cause and cardiovascular-specific mortality across all generations. However, the two nations exhibited divergent intergenerational trajectories. The US demonstrated "intergenerational divergence," with the fully-adjusted all-cause mortality hazard ratio (HR) for RII rising from 1.59 (95% CI 0.74–3.40) in the pre-1930s to 4.39 (1.91–10.09) in the post-1960s cohort. This widening gap was primarily mediated by lifestyle factors, with health insurance also playing a significant role in later generations. For CV mortality, the trend of intergenerational trajectories remained the same. Opposed to the US, China showed "intergenerational convergence," with HRs declining from 9.19 (2.95–28.62) in the 1930s to 1.17 (0.55–2.52) in the post-1960s. In China, cardiovascular metabolic factors historically suppressed inequality, while adverse lifestyle mediation became apparent in the youngest cohort.
Conclusion
Inequality in survival is dynamic. Widening disparities in the US necessitate interventions targeting behavioral risks and medical access. In China, narrowing gaps reflect structural improvements, yet emerging behavioral stratification suggests potential risks for renewed inequality in future generations.Association between SES and MortalityMediation proportion of risk factors