Unstable Income Tied to Heart, Mortality Risk

Income volatility may contribute to an increased risk of cardiovascular disease and death among young adults, a longitudinal study found.

Compared with a steady income, those with two or more drops in income by at least 25% from 1990 to 2005 had a significantly higher risk of death (HR 1.92 95% CI 1.07-3.44) and of cardiovascular disease (HR 2.54, 95% CI 1.24-5.19) from 2005 to 2015 after adjustment for cardiovascular risk factors, behavioral factors, and socio-demographics.

High income volatility (defined by an individual’s standard deviation of change from 1990-2005) was associated with a higher risk of death (HR 1.78, 95% CI 1.03-3.09) and of cardiovascular disease (HR 2.07, 95% CI 1.10-3.90) than low volatility, reported Adina Zeki Al Hazzouri, PhD, of the University of Miami, and colleagues in Circulation.

Patients with an unstable income “may subsequently be a high priority group for cardiovascular disease screening and interventions in a clinical setting,” the researchers emphasized.

Even slight changes in income can be pretty dramatic, and can often cause families a lot of hardship and a lot of stress, study co-author Tali Elfassy, PhD, also of the University of Miami told MedPage Today.

Such traumatic events or stress point are something to be aware of in patients, because clinicians can “then refer people appropriately to seek help in terms of potential stress relieving mechanisms,” Elfassy told MedPage Today.

Income volatility may affect behavior, access to medical care, and psychological stress, the researchers noted.

A growing body of evidence suggests that income volatility is linked with a number of unfavorable health outcomes like death and poor mental health, the investigators highlighted. “While income volatility and other longitudinal conceptualizations of income have gained recognition in medical research on the social determinants of health, in many epidemiologic studies, income is measured at a single point in time in the life course rather than repeatedly over time,” the study authors wrote.

Al Hazzouri’s group assessed 3,937 Coronary Artery Risk Development in Young Adults (CARDIA) study participants with a mean age of 30 in 1990. Of the participants, 47.6% were black and 56.2% were female. The study group was recruited from urban field centers in Chicago; Oakland; Minneapolis; and Birmingham, Alabama.

Participants were examined at baseline, with periodic follow-ups thereafter. They were contacted every 6 months to update their contact information and to report certain cardiovascular disease outcomes and vital status. The researchers used death certificates and medical records to adjudicated death and fatal and nonfatal cardiovascular disease events, which were mainly acute events related to stroke and heart disease.

From 2005 to 2015, there were 164 deaths and 106 incident cardiovascular disease events.

Not only was the data observational, but the income assessment was also a limitation, noted Elfassy. Because income was collected in brackets with ranges, “we did not have an exact measurement of income, which could create some sort of measurement error,” she told MedPage Today. However, any type of measurement error derived from this issue would probably tend to attenuate the results, rather than overestimate it, she added.

“Another potential limitation of this paper is we haven’t really explored mechanisms of action, we are really looking at income and not how this process of income fluctuation translated into health outcomes, we are not looking at the biological mechanism there,” Elfassy continued.

Considering the current economic climate and growing income instability, “understanding how income volatility is associated with health has become increasingly important,” the study authors wrote.

“Future studies focused on understanding mechanisms underlying the association between income volatility with CVD and mortality are warranted,” they concluded.