Heart disease has long been the largest killer in the United States. However, recent research suggests that it is only a matter of time before the second main cause of death – cancer – will become more lethal for the average person.
On the other hand, this is largely due to the fact that we have better prevented deaths from heart disease and life longer, not because the number of deaths from cancer increases.
Researchers from the Stanford University Medical Center analyzed data on deaths in the US in 2003-2015. At county level, they established the main cause of death for each year. In 2003, they found that heart disease was the main cause in 79 percent of the districts, but by 2015. This was only the main cause in 59 percent of districts.
Meanwhile, cancer was the leading cause of death in only 21 percent of districts in 2003, but by 2015. This number was up to 41 percent of districts.
"We are on the verge of moving from heart disease to cancer as the main cause of death," said lead author Latha Palaniappan CNN.
The team's findings, published on Monday in the Annals of Internal Medicine, are not particularly surprising.
Researchers from the Centers for Disease Control and Prevention, the federal agency responsible for publishing annual mortality data, have predicted that cancer will outweigh heart disease as the leading cause of death by 2020 (In 2016, the last year in which data is available public, there were 635.260 reported deaths due to heart disease and 598.038 deaths due to cancer).
This transformation was largely driven by a particularly deep decline in mortality from heart disease compared to other diseases. A study conducted, for example, at JAMA in 2016. It showed that the mortality rate of all causes across the country fell by 44 percent in 1969-2013, but by 68 percent in cases of heart disease in particular. In the same period, the death rate due to cancer decreased by 18 percent.
The same pattern was observed in the current study. After considering age and gender, mortality from heart disease dropped by 28 percent in 12 years, and the death rate from cancer dropped by 16 percent.
But looking at death at county level, Palaniappan and her team were able to see that this good news is not common. And as with many health-related issues, wealth plays an extremely important role. In counties where people recorded low median income, mortality from heart disease and cancer decreased significantly less than in high-income countries. Heart disease was also much more likely to remain the leading cause of death in these low-income poviats.
There is more than one reason for this vulnerability. Poorer people are more likely to smoke (and less likely to quit), which is one of the main risk factors for both heart disease and cancer. Low-income poviats may have poorer preventive and medical care, which makes it difficult for people to maintain their health or treatment because of acute heart problems.
Meanwhile, cancer is becoming more common, the older we get, so the fact that people in high-income counties are starting to die from it is a strange sign that they are living longer.
Death is of course a zero-sum game. The less we die of one thing, the more something else will end. However, emphasizing the socio-economic differences, the team hopes to pay more attention to everyone having the chance to live longer and healthier, regardless of the circumstances.
"We need to work harder in areas with lower income in the US so that they can observe the same improvement in mortality," said Palaniappan. CNN. "We need to focus more on heart disease and cancer prevention and treatment efforts, especially in African-American populations."
[Annals of Internal Medicine via CNN]