Global Health Inequalities in the Burden of Ischemic Stroke From 1990 to 2021

We read with great interest the study by Hou et al. [1], which was based on the Global Burden of Disease (GBD) Study 2021 and provided a comprehensive analysis of the burden of ischemic stroke at the global, regional, and national levels from 1990 to 2021. The findings revealed an overall declining trend in the incidence, mortality, and disability-adjusted life years (DALYs) associated with ischemic stroke worldwide. Notably, the study also identified a significant inverse association between the burden of ischemic stroke and gross domestic product. Therefore, leveraging existing data to quantitatively assess disparities and inequalities in the distribution of ischemic stroke across 204 countries and territories is crucial for promoting health equity and optimizing the allocation of healthcare resources.

The socio-demographic index (SDI), a composite of education, income, and fertility rates, reflects the link between socioeconomic development and public health [2]. Following World Health Organization (WHO) recommendations, we used the slope index of inequality and concentration index to assess absolute and relative inequalities in ischemic stroke burden across countries in relation to SDI [3]. The slope index was derived from a weighted regression of national DALYs rates against relative SDI ranks to account for heteroskedasticity. The concentration index was calculated by integrating the area under the Lorenz curve, based on cumulative population and DALYs distributions ranked by SDI.

Globally, significant absolute and relative inequalities persist in the burden of ischemic stroke across 204 countries and territories, disproportionately affecting nations with higher SDI levels. Over time, these inequalities have decreased. This reduction is particularly evident regarding absolute inequalities, as demonstrated by the decline in ischemic stroke DALYs rates from 668.5 (95% confidence interval [CI], 482.0–885.0) per 100,000 population in 1990 to 413.0 (95% CI, 270.9–555.0) in 2021 between the highest and lowest SDI countries (Figure 1A). Similarly, relative inequalities measured by the concentration index have slightly decreased from 0.24 (95% CI, 0.18–0.29) in 1990 to 0.21 (95% CI, 0.16–0.25) in 2021 (Figure 1B).

Overall, the positive values of the slope and concentration indices indicate that the burden of ischemic stroke remains primarily concentrated in relatively affluent countries and regions. The decreasing absolute values of these indices from 1990 to 2021 suggest a reduction in health inequalities and reflect a narrowing gap in disease burden between high- and low-income countries. However, significant disparities persist. This unequal distribution may be attributed to earlier population aging, a higher prevalence of lifestyle-related risk factors (such as high-salt diets, physical inactivity, and smoking), and greater access to healthcare services and diagnostic capacity in more socioeconomically developed countries. In response to this situation, the WHO, in its Global Action Plan for the Prevention and Control of Noncommunicable Diseases 2013–2020 [4], advocates prioritizing primary prevention within national health systems. This includes controlling hypertension, hyperlipidemia, and diabetes, as well as promoting healthy diets and physical activity. Therefore, only through the combined efforts of global policy support, strengthened health systems, and equitable resource allocation can we continue to reduce the overall burden of ischemic stroke and move toward achieving genuine health equity.

Chao Yang: methodology, validation, visualization, investigation, writing – original draft, project administration, formal analysis, software, data curation, supervision, resources, conceptualization, funding acquisition. Xiao Liu: conceptualization, investigation, writing – original draft, visualization, validation, methodology, software, formal analysis, project administration, resources, data curation, supervision. Jinyu Huang: writing – review and editing, funding acquisition, visualization, validation, methodology, project administration.

The authors declare no conflicts of interest.