Abstract Background Cross-national income–health gradients are well established, but it remains unclear whether they reflect improvements within countries over time or enduring structural differences between countries. Cardiovascular disease (CVD) mortality is also strongly shaped by population age structure, making demographic change central to the interpretation of economic development and cardiovascular outcomes. This study examined whether the association between GDP per capita and crude CVD mortality differs between countries and within countries over time after accounting for demographic structure. Methods This ecological panel analysis used country-year data for 200 countries from 1990 to 2023, yielding 6,800 observations. The outcome was the crude country-level CVD mortality rate per 100,000 population. Median age was used as an indicator of demographic structure, and GDP per capita from the World Bank World Development Indicators was used as an indicator of economic development. GDP-based models used complete observations because GDP per capita was missing for some country-years ( N = 5,407). Analyses included pooled regression, within–between decomposition, two-way fixed-effects models, nonlinear and interaction specifications, robustness checks, and descriptive residual analysis. Results Median age was strongly associated with crude CVD mortality across countries (B = 10.22 deaths per 100,000 for each additional year of median age, p < 0.001). In between-country models adjusted for demographic structure, higher GDP per capita was associated with lower CVD mortality (B = -82.20, p < 0.001). By contrast, within-country GDP growth showed no consistent protective association after demographic adjustment (B = -1.01, p = 0.68). GDP per capita moderated the association between median age and CVD mortality, with the ageing–mortality slope weaker at higher GDP levels. Residual analysis identified a persistent Eastern European cardiovascular mortality penalty that was not explained by median age alone. Conclusions The association between economic development and cardiovascular mortality changes meaning when examined across countries rather than within countries over time. Economic development should not be assumed to automatically reduce crude cardiovascular mortality unless the demographic structure, regional context, and the conversion of resources into capacity for prevention, treatment, and chronic disease management are made explicit.
NKULIKWA et al. (Sun,) studied this question.