The risk of having a stroke has gone down over the past 25 years among older people in the US, according to new research by Yao and colleagues published this month in Medical Care. The study combined data from several different nationally representative data sources, including Medicare claims and survey data from NHANES and MCBS. The study counted more than 1 million hospitalizations for ischemic stroke, caused by blockage or narrowing of the brain blood vessels; and nearly 150,000 hospitalizations for hemorrhagic stroke, caused by bleeding into or around the brain.
As shown in the figure, from 1988 to 2013 the age-adjusted risk of hospitalization for ischemic stroke (the more common type) dropped by roughly half among both black and white Medicare beneficiaries over age 65, with similar declines among both men and women.
Age-adjusted rates of first hospitalization for ischemic (A) and hemorrhagic (B) stroke in the US Medicare population aged 65 years or older, 1988–2013. Yao, Jamie; Ghosh, Kaushik; Perraillon, Marcelo C.; Cutler, David M.; Fang, Margaret C. Med Care; 57(4):262-269, April 2019. doi: 10.1097/MLR.0000000000001079
Hemorrhagic stroke hospitalization rates also declined in all four groups. Risk of both kinds of stroke in 2013 was highest for black women (solid black lines) and lowest for white men (dotted gray lines).
Both blacks and whites also had lower risks over time for dying within a month after hospitalization for ischemic stroke, with slightly greater improvements among black Medicare enrollees.
Stroke risk is influenced by a number of factors, including hypertension, smoking, and cholesterol levels. All of these risk factors have gone down over this same time period. In addition, people are taking more preventive medicines now, such as statins. As the authors point out, less smoking and more preventive care both count as big public health wins!
In addition, over this time period the US has seen improvements in quality measures for hospital-based acute stroke care. Public reporting and other efforts to increase quality, such as evidence-based guidelines, may have helped as well.
Yet as some risk factors have decreased, the prevalence of obesity and diabetes have increased — and those conditions may be harder to treat successfully. As measured by the Charlson comorbidity index (a composite measure of the prevalence of 19 conditions, each weighted by its associated mortality risk), the burden of morbidity has greatly increased among older Americans during the years of this study.
More remains to be done, as disparities between black and white Medicare enrollees persists even as the gap has narrowed.
Lisa M. Lines