Wealth and Income Provide Buffer against Stroke

By Charles Bankhead
ROTTERDAM, 25 april 2008 -- Money might not buy love, but it can protect some people against stroke, investigators found.
In a study of more than 1,500 stroke patients, wealth and income independently predicted stroke risk in people ages 50 to 64 but not in older individuals, Mauricio Avendano, Ph.D., of Erasmus University Medical Center here, reported in the May issue of Stroke.
Dr. Avendano and co-author M. Maria Glymour, Ph.D., of Harvard, suggested that the association they found between affluence and stroke probably understate the impact of social disparities on stroke risk.
Several studies have suggested that lower socioeconomic status is associated with higher stroke risk in developing countries. In the United States, however, the association goes in the opposite direction, as stroke disparities across education and income appear to reverse at age 74, the authors said.
Almost 90% of strokes occur after 65, but the influence of socioeconomic status on stroke risk in that older age group had not been examined, they continued.
So Drs. Avendano and Glymour analyzed data from the Health and Retirement Study, a longitudinal survey of a national sample of U.S. adults 50 and older. They included 19,965 participants who were stroke-free at baseline.
Baseline assessments of wealth, income, and education were included in a Cox proportional hazards model to predict time to stroke.
Separate models were developed for the age groups 50 to 64, 65 to 74, and 75 and older, incorporating known stroke risk factors.
During a mean follow-up of 8.5 years, 1,542 participants had strokes.
Higher education predicted a reduced stroke risk in the age group of 50 to 64, but not after adjustment for wealth and income.
In contrast, wealth and income were independent predictors of stroke in that age group.
Participants in the lowest category for wealth (less than $1,000) and annual income ($5,657) had a relative stroke risk of 2.3 and 1.8, respectively, compared with participants in the highest category ($344,499 or more and $56,993 a year or more).
After adjustment, the hazard ratios for wealth (HR 1.7, 95% CI 1.2 to 2.5) and income (HR 1.6, 95% CI 1.2 to 2.3) remained significant.
Wealth, income, and education did not consistently predict stroke risk after age 65, however.
"The role of income and wealth may appear limited from a public health perspective because these factors are not related to stroke beyond age 65," the authors concluded.
"However," they said, "the age-attenuation of socioeconomic disparities in stroke likely reflects selective survival, a consequence of the cumulative disadvantage faced by individuals through the life-course."
"Policies that improve economically disadvantaged groups' access to basic resources before reaching old age might reduce stroke rates as these cohorts age," they said.
"Alternatively, enhancing opportunities for low socioeconomic status individuals to accumulate assets before retirement age might help reduce stroke rates and ameliorate socioeconomic status disparities in stroke."
The study was supported by the U.S. National Institute of Aging. The authors reported that they had no disclosures.

Primary source: StrokeSource reference:Avendano M, Glymour MM "Stroke disparities in older Americans. Is wealth a more powerful indicator of risk than income and education?" Stroke. 2008; DOI:10.1161/STROKEAHA.107.490383.