Wealth and income are independent predictors of stroke from ages 50 to 64 but do not predict stroke among the U.S. elderly, which reflects a buffering of the negative effect of low socioeconomic status by improved access to social and healthcare programs at old ages, according to a study in the May issue of Stroke.
Mauricio Avendano, PhD, from the department of public health at Erasmus Medical Center in Rotterdam, Netherlands, and M. Maria Glymour, ScD, from the Harvard School of Public Health in Boston, conducted the study. They examined the independent effect of wealth, income and education on stroke, and how the disparities evolve throughout middle and old age in a representative cohort of older Americans.
They also noted that almost 90 percent of strokes occur after 65, but the influence of socioeconomic status on stroke risk in that older age group has previously not been examined.
The researchers followed stroke-free participants in the Health and Retirement Study (19,565) for an average of 8.5 years.
In order to assess the results, Avendano and Glymour assessed the total wealth, income and education used in Cox proportional hazards models to predict time to stroke. Also, the investigators estimated the separate models for three age-strata (50 to 64, 65 to 74 and older than 75), and incorporating risk factor measures (smoking, physical activity, body mass index, hypertension, diabetes and heart disease).
Out of the 19,565 patients, 1,542 subjects developed incident stroke, the authors wrote.
The researchers found that higher education predicted reduced stroke risk at ages 50 to 64, but not after adjustment for wealth and income. Wealth and income were independent risk factors for stroke at ages 50 to 64, according to the investigators. Adjusted hazard ratios comparing the lowest decile with the 75th-90th percentiles were 2.3 for wealth and 1.8 for income. Risk factor adjustment attenuated these effects by 30 to 50 percent, but coefficients for both wealth and income remained significant, the researchers said.
The authors noted that “wealth, income and education did not consistently predict stroke beyond age 65.”
“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 Avendano and Glymour concluded.
“However, 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,” the authors wrote. “Policies that improve economically disadvantaged groups’ access to basic resources before reaching old age might reduce stroke rates as these cohorts age," they noted.
“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,” Avendano and Glymour concluded.