A new study by scientists in the US and the UK shows that the rate of deaths due to heart disease in young American adults has reached a plateau and may even be going up again in young women, after decades of hard won progress in reducing it. Researchers suggest the worrying trend could be due to bad health habits.

The study is the work of researchers from the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, US, and the University of Liverpool in the UK, and is published in the 27th November issue of the Journal of the American College of Cardiology (JACC).

The levelling off of death rates due to heart disease among America’s young adults coincides with increasing rates of obesity, diabetes, high blood pressure, and other cardiovascular risk factors said the researchers.

Study co-author and medical officer with the US Public Health Service, Dr Earl S Ford said:

“Young adults should take stock of their lifestyles.”

“If you’re smoking, you should quit. If you’re doing less than 30 minutes of physical activity per day, it’s time to find ways to be more active. If you need to lose weight, you should burn more calories than you take in,” he warned.

Ford and study co-author, Dr Simon Capewell of the Department of Public Health, University of Liverpool, UK, analysed US vital statistics from 1980 to 2002 for people aged 35 and older.

The big picture told a good news story: the death rate from heart disease went down by 52 per cent in men and 49 per cent in women over the period.

The year by year figures also looked good overall. Death rates from heart disease among men declined, on average, by 2.9 per cent a year during the 1980s, by 2.6 per cent a year in the 1990s, and 4.4 per cent a year in 2000 to 2002. Among women too, the overall picture showed a gradual year on year decline: the average annual death rate went down by 2.6, 2.4 and 4.4 per cent in those same periods.

The not so good story, however, emerged when the researchers broke the figures down by age.

For men aged 35 to 54 the average yearly death rate from heart disease went down by 6.2 per cent in the 1980s, slowed to 2.3 per cent in the 1990s, and reached a near plateau of 0.5 per cent annual reduction between 2000 and 2002.

For women aged 35 to 54 the news is worse. The average annual decline in deaths due to heart disease fell by 5.4 per cent in the 1980s, slowed to 1.2 per cent in the 1990s, and actually rose again by an annual average of 1.5 per cent during 2000 to 2002. However, the increase was not statistically significant and all that can be said with confidence is that the figures have levelled off.

However, among the younger women, aged 35 to 44, there was an average annual rise in heart disease deaths of 1.3 per cent during 1997 to 2002, and this figure was shown to be statistically significant, so the researchers can say with more confidence that there appears to be a worrying rising trend among female adult Americans in their late 30s and early 40s, of deaths due to heart disease.

In contrast, among older men and women, aged 55 and over, the researchers estimated that the annual percentage decrease in death due to heart disease “accelerated in more recent years compared with earlier periods”.

Ford and Capewell concluded that:

“The mortality rates for CHD [coronary heart disease] among younger adults may serve as a sentinel event. Unfavorable trends in several risk factors for CHD provide a likely explanation for the observed mortality rates.”

Commenting in an editorial in the same issue of the journal, Dr Philip Greenland, who is Harry W Dingman Professor and senior associate dean for clinical and translational research at the Feinberg School of Medicine in Northwestern University, Chicago, wrote that:

“This should be regarded as a wake-up call for everyone interested in heart disease and heart health.”

“The take-home message is that heart disease has not gone away, continues to be a problem, and could become a greater problem if Americans fail to pay attention to known warning signs like overweight and obesity, and lack of exercise,” he observed.

Ford said good health habits should start early:

“Atherosclerotic changes that lead to coronary heart disease occur at an early age.”

“Therefore, it’s especially important that children learn to develop appropriate behaviors that minimize their risk for heart disease later in life. Cardiovascular health is a life-long commitment,” he added.

“Coronary Heart Disease Mortality Among Young Adults in the U.S. From 1980 Through 2002: Concealed Leveling of Mortality Rates.”
Earl S. Ford, and Simon Capewell.
J Am Coll Cardiol, 2007; 50:2128-2132.
27 November 2007.

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Written by: Catharine Paddock