Poverty Linked to 42% Increased Mortality Risk in US

Credit: Unsplash / Jon Tyson

Current poverty in the US is associated with a 42% increased hazard of mortality than the general, non-poverty population, according to new research.¹

In a longitudinal survey analysis of national income and mortality data spanning 1997 – 2019, a team of multinational investigators observed findings that would implicate poverty as a major risk factor for death among Americans. In fact, their findings showed persons who have spent 10 years consecutively at or below the poverty line were at a 71% increased risk of death.

The team, led by David Brady, PhD, of the School of Public Policy at University of California, Riverside, sought to estimate the link between poverty and mortality, as well as the proportion and total deaths associated with poverty in the US. Seeing as the country has a significantly greater poverty rate than its peers, Brady and colleagues described it as an “enormous challenge to population health” given the understood link between poverty and poor health.

“Despite valuable contributions of prior research on income and mortality, the quantity of mortality associated with poverty in the US remains unknown,” they noted.

The investigators analyzed data from the Panel Study of Income Dynamics, 1997 – 2019, to interpret poverty rates in the US. Poverty was defined as <50% the median income. Current poverty was interpreted annually, while cumulative poverty was the proportion of an individual’s income over 10 years. Unique to similar studies, the team used all sources of income—including cash and near-cash transfers, taxes and tax credits—to measure household income adjusted for household size.

Mortality from surviving family members was observed and validated via the National Death Index. The team adjusted for self-rated health, overweight or obesity status, smoking status, acute health events, chronic disease and other confounders.

Brady and colleagues observed greater mortality hazard ratio (HR) of 1.42 among Americans in current poverty (95% CI, 1.26 – 1.60). Cumulative poverty was associated with a mortality HR of 1.71 versus Americans never in poverty over 10 years (95% CI, 1.45 – 2.02).

Only heart disease, cancer and smoking status were associated with a greater amount of US deaths among persons aged ≥15 years old in 2019 than cumulative poverty’s estimated total of 295,431 (95% CI, 193,652 – 406,007). Current poverty was associated with an estimated 183,003 deaths among this same population (95% CI, 116,713 – 254,507), a total that would be greater than deaths associated with stroke, Alzheimer disease, diabetes and drug overdoses.

“Cumulative poverty was associated with approximately 60% greater mortality than current poverty,” investigators wrote. “Hence, cumulative poverty was associated with greater mortality than even obesity and dementia. Heart disease, cancer, and smoking were the only causes or risks with greater mortality than cumulative poverty.”

What’s more, investigators noted a divergence in the survival curve between individuals in poverty versus those not in poverty at approximately 40 years old. The curve gap peaks near 70 years old, when it begins to less and converge again near 90 years old.

The team concluded that their estimates, combined with the US’ historically high rates of consistent poverty, may help explain the country’s comparatively lower life expectancy.

Data from April 2022 showed that the overall life expectancy of Americans decreased by a median 1.87 years from just 2019 – 2020, which would have been a 3-fold worse decrease than the mean decreases of 21 peer countries. The data also showed significantly worsened life expectancies among Hispanic and non-Hispanic Black populations in the US.²

Brady and colleagues noted that, because some ethnic and racial minority groups are at a significantly greater likelihood to experience poverty, their estimates may also contribute to understanding inequities in life expectancy as with the April 2022 report.

“Moreover, poverty likely aggravated the mortality impact of COVID-19, which occurred after our analyses ended in 2019,” they noted. “Therefore, one limitation of this study is that our estimates may be conservative about the number of deaths associated with poverty.”

The team stressed their proposal that poverty be considered a major US mortality risk factor going forward, noting that benefit-cost calculations for policies targeting poverty reduction should also consider the benefits of lowered mortality rates based on the association.

References

1. ^{Brady D, Kohler U, Zheng H. Novel Estimates of Mortality Associated With Poverty in the US. JAMA Internal Medicine. Published online April 17, 2023. Accessed April 17, 2023. doi:10.1001/jamainternmed.2023.0276}
2. ^{Kunzmann K. US Life Expectancy Significantly Dropped Compared to Peer Countries in 2020. HCPLive. Published April 13, 2022. Accessed April 17, 2023. https://www.hcplive.com/view/us-life-expectancy-significantly-dropped-compared-peer-countries-2020}