Cancer overtakes cardiovascular diseases as number one killer in high-income countries
According to the World Health Organization (WHO), cardiovascular diseases (CVDs) are the leading cause of death globally. But now a new contender is rising, and it’s not a surprising one: cancer. A major new study has compared the causes of death in dozens of high-, middle- and low-income countries (HIC, MIC and LIC) over a decade and found that cancer has overtaken CVDs as the number one killer in some high-income countries.
The Prospective Urban and Rural Epidemiologic (PURE) study was the basis for two new reports on the global state of health. The first followed 162,534 adults aged between 35 and 70, between 2005 and 2016. These participants were fairly evenly split along gender lines, with 58 percent women, and lived across 21 countries – four high-income, 12 middle-income, and five low-income.
The rates of CVD occurring were found to be 7.1 per 1,000 person years in LIC, 6.8 in MIC and 4.3 in HIC. Interestingly though, cancer, pneumonia, injuries and chronic obstructive pulmonary disease (COPD) were found to be at their highest in HIC and lowest in LIC.
Overall, deaths were twice as common in LIC than in MIC, and four times higher than HIC. Deaths from cancer stayed pretty similar across all income levels, meaning in HIC they made up a higher proportion of deaths than CVDs.
The researchers say that the discrepancy between deaths from CVDs in high- to low-income countries is likely a matter of healthcare. The risk factors aren’t any higher in LIC, but CVDs are less likely to be treated and managed than in HIC, and therefore are more lethal.
The second study focused on the risk factors of CVDs. It followed 155,722 people with no prior history of CVD in those same 21 countries. The team found that 70 percent of CVD cases worldwide could be attributed to risk factors that could be modified – and therefore prevented.
For deaths, behavioral risk factors were the biggest contributor, accounting for 26.3 percent of deaths across all income levels. But for LIC and MIC, factors like air pollution, poor diet and low education had significantly higher impacts than in HIC. The factors playing bigger roles in HIC were metabolic, such as high cholesterol, obesity and diabetes.
“We have reached a turning point in the development of CVD prevention and management strategies,” says Annika Rosengren, coordinator of the study. “While some risk factors certainly have large global impacts, such as hypertension, tobacco, and low education, the impact of others, such as poor diet, household air pollution, vary largely by the economic level of countries. There is an opportunity now to realign global health policies and adapt them to different groups of countries based on the risk factors of greatest impact in each setting.”
As intriguing as the two studies are, there are a few caveats to keep in mind. Although they both involved quite a large sample size over a long period, the country selection may have influenced the results somewhat. No participants were taken from the US, UK, or Australia, and there were fewer people sampled in Africa and the Middle East. With this in mind, generalizing results across all countries is not wise.
Still, it provides a comprehensive starting point and may inspire countries to devote more resources to the risk factors for CVD and cancer that have the biggest potential impact on each region. In fact, WHO announced just this week that it was revising models of CVD risk in different countries.
While CVD remains the biggest killer of people worldwide, the new research suggests it may not hold the crown for long.
“The world is witnessing a new epidemiologic transition among the different categories of non-communicable diseases (NCD), with CVD no longer the leading cause of death in HIC,” says Gilles Dagenais, lead author of the first report. “Our report found cancer to be the second most common cause of death globally in 2017, accounting for 26 percent of all deaths. But as CVD rates continue to fall, cancer could likely become the leading cause of death worldwide, within just a few decades.”