Global Variation in the Relative Burden of Stroke and Ischemic Heart Disease

Study Questions:

What is the international variation in the burden of stroke versus ischemic heart disease (IHD), and how does this relate to the prevalence of risk factors and sociodemographic factors?

Methods:

The authors analyzed data from World Health Organization Global InfoBase, the WHO Global Burden of Disease Program (GBD), and the World Bank. Estimates of disease burden for IHD and stroke, as measured by disease-related mortality and disability-adjusted life-year (DALY) loss rates, were compiled from WHO GBD estimates for each country, with age and sex standardized to the WHO global standard. National prevalence of vascular risk factors was compiled from the WHO Global InfoBase, and national income data were derived from World Bank estimates. Linear regression for univariable analysis and the Cuzick test for trends were performed for analysis.

Results:

Among 192 WHO member countries, stroke mortality exceeded IHD mortality in 74 countries (39%), and stroke DALY rates exceeded IHD DALY rates in 62 countries (32%). Stroke mortality ranged from 12.7% higher to 27.2% lower than IHD mortality, and stroke DALY loss ranged from 6.2% higher to 10.2% lower than for IHD. Stroke burden of disease was disproportionately higher in China, Africa, and South America, while IHD burden of disease was higher in the Middle East, North America, Australia, and much of Europe. Lower national income was associated with higher mortality (p < 0.001) and higher burden of disease (p = 0.001) from stroke. Diabetes and total cholesterol were associated with greater IHD burden, even after adjusting for national income.

Conclusions:

The authors concluded that substantial global variation in the relative burden of stroke versus IHD exists. They also concluded that the disproportionate burden from stroke in many lower-income countries suggests that distinct interventions may be required.

Perspective:

This interesting study, by exploiting comprehensive international epidemiologic and socioeconomic databases, offers a unique perspective on the relationship between sociodemographic factors, and the presence of disproportionate risk for stroke disease versus IHD. The observation that stroke and IHD burden and mortality do not track with each other, may offer insights into the relative effectiveness of preventive interventions for each disease. The association between lower national income and higher relative stroke burden may suggest differential benefit of health care interventions in the prevention and treatment of stroke versus IHD. On the other hand, vascular risk factors associated with higher national income—e.g., diabetes, obesity, and dyslipidemia—may explain the higher relative IHD burden in such nations. As with most observational studies, this one generates far more questions than it answers, but certainly offers worthy hypotheses for further study. Risk factor disparities observed identify opportunities for population health improvement, which will be very important as the global epidemic of cardiovascular disease expands rapidly into lower income countries.

Clinical Topics: Dyslipidemia, Atherosclerotic Disease (CAD/PAD), Lipid Metabolism, Nonstatins

Keywords: Coronary Artery Disease, North America, Myocardial Ischemia, Stroke, World Health Organization, South America, Risk Factors, Europe, Prevalence, Cholesterol, China, Australia, Cardiovascular Diseases, Obesity, Middle East, Diabetes Mellitus


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