Heart disease is the leading cause of death for both men and women in the United States, according to the Atlanta-based Centers for Disease Control and Prevention. And there are multiple risk factors linked to the disease, including diabetes, high blood pressure, smoking and obesity.
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Now new research suggests fluctuating personal income may be associated with an increased risk of heart disease as well.
"Income volatility presents a growing public health threat, especially when federal programs, which are meant to help absorb unpredictable income changes, are undergoing continuous changes, and mostly cuts," lead author Tali Elfassy of the University of Miami Miller School of Medicine in Florida said in a statement.
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The cohort study, funded in part by grants from the National Institutes of Health and the American Heart Association, was recently published in the AHA journal Circulation.
Researchers sought to understand the effects of rising income volatility as a public health problem by examining fluctuating income in 3,937 white and black adults aged 23-35 at the start of the study (1990) through 2005. Between 2005 and 2015, they used medical records or death certificates to assess fatal and non-fatal cardiovascular incidents and causes of death.
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The data comes from the ongoing Coronary Artery Risk Development in Young Adults study, which has participants in Birmingham, Alabama; Minneapolis; Chicago and Oakland, California.
For the study, scientists measured income volatility as the percent change in income from one measurement to the next and defined a drop in income as a decrease of 25 percent or more from the previous assessment.
They ultimately found that significant income fluctuations and drops during a 15-year period of formative earning years nearly doubled the risk of early death and more than doubled the risk for cardiovascular diseases, such as heart attacks or strokes in the subsequent 10 years.
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Previous research has shown that low income is associated with various unhealthy conditions and behaviors, including depression, stress, high blood pressure, alcohol use, smoking and inadequate physical activity, all of which can increase risk of heart disease and early death. Additionally, authors note, individuals with fluctuating, unpredictable income may not have the “protective benefit of social networks or coping resources” many persistently low income communities may have.
The new research, albeit observational in nature and therefore not proving cause and effect, reveals “a clear graded relationship such that risk of CVD and all-cause mortality was greater with increased exposure to economic adversity, after accounting for multiple socioeconomic factors and cardiovascular risk factors,” authors wrote. “Taken together, these findings suggest that income volatility and income drops experienced in early to mid-adulthood are important independent predictors of CVD risk and overall mortality.”
Possible limitations
Authors note more research is needed to understand associations of income volatility across other racial and ethnic groups, as well as rural Americans. Future studies should also examine differences and interactions by sex, race or baseline socioeconomic status.
Another limitation, researchers point out, is that income volatility as they defined it doesn’t differentiate between positive and negative volatility, though they conducted additional analyses to confirm fluctuating income in any direction was associated with an increased risk of heart disease.
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