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Sudden cardiac death

Study
Results
Comment

It becomes obvious when one begins to write about risk, as Bandolier has been doing in recent issues, that some sort of background is needed. Risk examines mainly serious consequences, most often death. While Keynes' dictum about us all being dead in the long run is all very well, it is the short run that we worry about most.



Figure 1: Risk of death in UK by age and sex, for 2003. Open symbols, women; solid circles, men





So what is the chance of us dying tomorrow, from anything, or from something? Figure 1 shows UK data on mortality from 2003, by age and by sex. It tells us what we already know, that our risk of dying increases as we get older, and is higher for men (filled symbols) than women (open symbols) at almost all ages. Of course, these are averages, and people leading healthy lifestyles are likely always to have lower risk than those who do not.

What about looking at particular causes of death? Governments produce lots of useful information, and in the UK there have been impressive reductions since 1979 in death rates for both sexes, at almost all ages, but especially in middle age, and from many causes. But if we want answers to more specific questions, we have turn to the epidemiologists. So let's look at sudden cardiac death, where definitions have changed in recent years, with the time interval between onset of symptoms and death reduced from 24 to one hour.


Study

The study [1] was conducted in Holland using an electronic database of about 500,000 people registered with a general practitioner. The records contain coded comprehensive and anonymous data that allows for epidemiological studies. In this case the study was over six years, from 1995 to 2001, in people aged 18 years or older, registered for at least one year. Medical records of all deaths were examined to classify the circumstances, whether the death could be classified as cardiac, and whether people were previously in good health. Only deaths from suicide and in patients with cancer were excluded from examination.


Results

The final population was 250,000 people, with a median age of 40 years, and 51% female. There were 4,892 deaths, of which 582 (12%) were probable sudden cardiac deaths. The median age of cases was 72 years, with 59% male. The median age of male cases was 70 years, compared with 76 years for female cases.

Sudden death was witnessed in 354 cases, with 76% occurring in the home, 14% in a public place and 5% in an ambulance or on arrival at hospital. In the 228 unwitnessed cases, the majority occurred at home when a place was mentioned.

The incidence of sudden cardiac death declined slightly over the period (Figure 2). The incidence increased with age in women and men (Figure 3), with and age adjusted rate of 2.3.



Figure 2: Incidence of sudden cardiac death in Holland, by year







Figure 3: Incidence of sudden cardiac death in Holland, by age and sex





The incidence was highest in October, and lowest in August, with more cases on Mondays and Tuesdays than Thursdays.


Comment

As always, it is useful to recognise that stuff happens. Whoever and wherever we are, bad things can come out of that blue sky, sometimes without any warning. For men over the age of 70 years, 1 in 100 are likely to have a sudden cardiac death each year. For men in their 60s, sudden cardiac death runs at about 2 per 1000, or 1 in 500. That is 40 times more likely than being killed in a road traffic accident.

So if we put our seat belts on when we drive to keep us safe, and avoid doing crazy things on the road, it makes even more sense to avoid doing crazy things with our hearts. Not smoking, eating healthily, and a modicum of exercise and alcohol makes sense, really. If a behaviour is less risky than driving (chance of dying 1 in 20,000 per year) we probably accept it. Having an unhealthy lifestyle is much, much, more risky than that.

Reference:

  1. SM Straus et al. The incidence of sudden cardiac death in the general population. Journal of Clinical Epidemiology 2004 57: 98-102.

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