Big Drop in Incidence and Fatality of MIs in England Reply

Since 2002 in England the incidence of acute MI has dropped by one-half and the case fatality rate by one-third, according to a new study published in BMJ. The overall decline in deaths from MI are about equally due to improvements in the prevention of MI and the treatment of MI.

Kate Smolina and colleagues analyzed data from 861,134 acute MI patients in England from 2002 through December 2010. Over the course of the study period, the MI event rate declined:

  • in men by 33%, from 230 to 154 per 100,000, for an average annual decline of 4.8%
  • in women by 31%, from 95.4 to 66 per 100,000, for an average annual decline of 4.5%

Similarly, the case fatality rate also declined:

  • in men by 24%, from 42.0% to 32.1%, for an average annual decline of 3.6%
  • in women by 29%, from 42.2% to 29.9%, for an average annual decline of 4.2%

The authors reported that for middle aged people the decline in the event rate played a bigger role in the changes, but for younger and older people the case fatality played a bigger role.

In an accompanying editorial, Hugh Tunstall-Pedoe writes that the progress made in England and other western countries has not been replicated elsewhere:

As the world population ages and becomes more industrialised and urbanised, the decline in coronary mortality is predominantly in rich nations, while rates increase in dozens of others. Can these countries learn from us, or must they repeat our mistakes?

Here is the press release from BMJ:

Deaths from heart attacks halved in last decade

Research: The determinants of the decline in mortality from acute myocardial infarction in England between 2002 and 2010: a national database study. 

Editorial: The decline in coronary heart disease; did it fall or was it pushed?

The death rate from heart attack in England has halved in the last decade, claims a research paper published today on bmj.com.

Compared with earlier years, the study found there were fewer heart attacks in the last decade and fewer of these were fatal.

Several studies have already investigated changes in deaths from heart attack in many countries around the world, but reasons for the decline in deaths in England are still not known. Researchers from the University of Oxford set out to identify the possible causes of this reduction.

Using national hospital and mortality data, they looked at 840,175 men and women in England who had suffered from a total of 861,134 heart attacks between 2002 and 2010. Overall, the death rates for heart attacks fell by 50% in men and 53% in women.

The researchers investigated how much of the decline in death rates resulted from a decrease in the occurrence of new heart attacks, and how much was a result of improved survival after heart attack. They concluded that just over half of the decline in total death can be attributed to a decline in the number of new heart attacks, and just under half to a decline in the death rate after heart attack.

The substantial drop in the rate of occurrence of heart attacks reflects the impact of both primary and secondary prevention through beneficial changes in the health of the population with respect to cardiovascular risk factors, say the researchers, while the improvements in death rates following hospital admission are likely to reflect major improvements in NHS care over the recent years.

61% of the people who experienced heart attack were men, 36% of heart attack cases were fatal and 73% occurred in those aged 65 and over. Out of 311,419 fatal heart attacks, 70% were sudden deaths that occurred without an admission to hospital.

The factors behind the decrease in heart attack mortality differed by age, sex and geographic area. The greatest declines in heart attack event rate and mortality were seen among middle-aged individuals, whereas the smallest declines were seen for the younger and older age groups in both men and women. Rising rates of obesity and diabetes may help explain the lack of improvement in the occurrence of heart attacks among the youngest age group.

The authors say that further research is required to gain a clearer understanding of the specific elements of prevention and treatment that have contributed to the fall in death rates.

In an accompanying editorial, Hugh Tunstall-Pedoe from the Institute of Cardiovascular Research at the University of Dundee argues that death rates from heart attacks have only fallen in “rich nations” whereas they continue to rise in many others. He suggests that more data is needed from the other countries to reach a conclusion, but that resources to obtain data are scarce.

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