Living in poverty with chronic inflammation significantly increases heart disease and cancer mortality risk, a new US study has found.
The University of Florida research showed that health outcomes for Americans living in poverty and with chronic inflammation are significantly worse than expected from their separate health effects.
Lead author Dr Arch Mainou is a professor at the University of Florida.
The researcher said: “Here we show that clinicians need to consider the effect of inflammation on people’s health and longevity, especially on those experiencing poverty.”
Inflammation is a natural physiological reaction to infections or injuries and is essential for healing.
But chronic inflammation – caused by exposure to environmental toxins, certain diets, autoimmune disorders such as arthritis, or other chronic diseases like Alzheimer’s – is a known risk factor for disease and mortality, much like poverty.
In the study, researchers analysed data from adults aged 40 and older, enrolled between 1999 and 2002 in the National Health and Nutrition Examination Survey (NHANES), and followed them until 31 December 2019.
The survey, conducted since 1971 by the National Center for Health Statistics, tracks the health and nutritional status of US adults and children.
The survey allows for estimates of the US population represented by the cohort, and this study represented nearly 95 million adults.
The authors combined NHANES data with records from the National Death Index, to calculate mortality rates over a period of 15 years after enrolment.
NHANES records the household income, among other demographics. The authors divided this by the official poverty threshold to calculate the ‘poverty index ratio’ – a standard measure of poverty.
Whether participants suffered from severe inflammation was deduced from their plasma concentration of high sensitivity C-reactive protein (hs-CRP), which is produced by the liver in response to the secretion of interleukins by immune and fat cells.
The concentration of this protein, included among NHANES data, is a readily available, informative, and well-studied measure of inflammation: for example, elevated concentrations are known to increase the risk of cardiovascular disease and all-cause mortality.
The researchers classified participants in four groups: with or without chronic inflammation, and living below the poverty line or not.
By comparing the 15-year mortality rate between these, they could therefore study the effects of poverty and inflammation separately and jointly.
Dr Frank A. Orlando is an associate professor at the University of Florida and the study’s second author.
He said: “We found that participants with either inflammation or poverty alone each had about a 50 per cent increased risk in all-cause mortality.
In contrast, individuals with both inflammation and poverty had a 127 per cent increased heart disease mortality risk and a 196 per cent increased cancer mortality risk.
“If the effects of inflammation and poverty on mortality were additive, you’d expect a 100 per cent increase in mortality for people where both apply.
“But since the observed 127 per cent and 196 per cent increases are much greater than 100 per cent, we conclude that the combined effect of inflammation and poverty on mortality is synergistic.”
A wide variety of treatments for systemic inflammation exist, ranging from diet and exercise to nonsteroidal anti-inflammatory drugs (NSAIDs) and steroids.
The new findings suggest that clinicians might consider screening socially disadvantaged people – already a medically vulnerable group – for chronic inflammation, and if necessary treat them with such anti-inflammatory drugs.
However, steroids and NSAIDS aren’t without risks when used long-term.
More research will therefore be needed before patients are routinely prescribed them in clinical practice to decrease systemic inflammation.
Mainous said: “It’s important for guidelines panels to take up this issue to help clinicians integrate inflammation screening into their standard of care, particularly for patients who may have factors that place them at risk for chronic inflammation, including living in poverty.
“It is time to move beyond documenting the health problems that inflammation can cause, to trying to fix these problems.”
