For decades, deaths caused by cardiovascular events, such as stroke, had been on the decline in high income countries. Recently, however, this decline has come to a halt, and some countries are even experiencing rising rates of stroke and heart disease-related deaths. Why?
"In high income countries, the very substantial decline in [cardiovascular] mortality over the past half-century has been a major, yet often unheralded, global public health achievement."
This is what Prof. Alan Lopez and Tim Adair, Ph.D. write in the introduction to a new study paper, published in the International Journal of Epidemiology. The journal reviews current trends in mortality associated with stroke, heart disease, and other cardiovascular diseases (CVD).
Prof. Lopez and Adair, from the University of Melbourne in Parkville, Australia, note that "recent evidence from national vital statistics systems in these countries suggests that the long term decline in CVD and specifically heart disease mortality may be stagnating, with rates even rising in some populations, particularly at ages [of under] 75 years."
The researchers looked at vital statistics recorded from 2000 onwards in 23 high income countries. These are Australia, France, Japan, Spain, Austria, Germany, the Netherlands, Sweden, Belgium, Greece, New Zealand, Switzerland, Canada, Ireland, Norway, United Kingdom, Denmark, Israel, the Republic of Korea, the United States, Finland, Italy, and Singapore.
These statistics all came from the World Health Organization (WHO) Mortality Database and included mortality rates related to cardiovascular events.
Obesity trends may play key role
Lopez and Adair found that the rate of decline in CVD-related mortality has slowed down 'considerably' in 12 of the high income countries they investigated in their study. This, in particular, was the case for adults aged 35–74.
Moreover, the most recent data show that CVD death rates have increased for females in the U.S. and Canada over the last year. In Australia, the U.K., and New Zealand, the decline in cardiovascular mortality has slowed down from year to year.
So, why are people once more at an increased risk of premature death due to events such as stroke and heart disease, even in the richer countries of the world?
Prof. Lopez and Adair have a theory. They believe that part of the answer lies in the ever increasing rates of obesity that coincide with the trends in stroke and heart disease mortality.
"Each of these countries has very high levels of obesity. In Australia, close to one-third of adults are obese," notes Prof. Lopez.
"These increases in obesity levels mean that a significant portion of the population has been exposed to the cardiovascular disease risks associated with being overweight for several decades," he continues.
However, not all high income countries face an obesity epidemic. For instance, the researchers point out that Italy and France report the lowest number of cases of obesity among the 23 countries featured in the current study.
A threat to future life expectancy rates
This is why the researchers believe that obesity may only be one part of the problem. The rest may come down to the prevalence of other risk factors for cardiovascular problems, such as smoking, high blood pressure, and high cholesterol.
"Obesity, of course, is likely to be only a partial explanation; Italy and France, where the deceleration in [cardiovascular] mortality in recent years is among the most notable [...], each has below-average obesity levels but higher smoking prevalence among both men and women," the researchers write in their paper.
Going forward, the two authors suggest that countries should invest more in inputting preventive strategies and advising their citizens on the most healthful lifestyle choices.
"In order to combat this, significant investment in preventive health measures is needed, particularly those aimed at increasing physical activity, improving diet and reducing obesity," says Adair.
"Failure to address these issues could confirm the end of the long term decline in cardiovascular disease deaths and threaten future gains in life expectancy."
Tim Adair, Ph.D.