North-South divide in heart disease deaths
‘New study finds heart disease has halved since the 1980s – but Northerners are more likely to suffer stroke or [heart] attack,’ the Daily Mail reports.
The story comes from a study that looked at the death rates from cardiovascular diseases (CVD), such as heart attacks and strokes, in every area of England over a 25-year period.
CVDs are the leading cause of death in the UK. This report focused on the differences in death rates between the most and least deprived communities and how these have changed over time. It found that overall, deaths from CVDs have declined in most areas, but that the reduction in CVD deaths varied substantially by area.
It also found that among young and middle-aged adults, the gap in death rates between the most and least deprived areas narrowed over time. But for those aged 65 and over, the decline in death rates was smaller in the most deprived communities than in the least deprived, resulting in a widening gap in mortality between rich and poor.
Broadly, places with the highest death rates were in areas around Manchester and Liverpool, larger parts of Yorkshire and Birmingham and deprived boroughs of London, such as Hackney. Outside of London, death rates were generally lower in southern England.
This is a complex report. It reveals that while most areas of England have seen a decline in death rates from cardiovascular disease, the gains have not always been shared equally. The authors warn that the economic downturn combined with ongoing austerity measures could slow down the recent decline in deaths from heart disease.
Where did the story come from?
The study was carried out by researchers from Imperial College London, the University of Ionannina in Greece and the University of Valencia in Spain, and published in the peer reviewed International Journal of Epidemiology. It was funded by a number of public institutions, including the Medical Research Council and the Health Protection Agency.
This complex statistical report was reported fairly. Most papers highlighted the inequalities in CVD death rates – with many commentators highlighting an alleged North-South divide in terms of health inequalities. But the Express’ report that thousands more are dying of heart disease in poorer areas is oversimplistic. The study was looking at the differences in the decline in CVD death rates per 100,000 population between the least and most deprived areas, not the actual numbers dying.
What kind of research was this?
The authors say that while it is known that death rates from cardiovascular disease have more than halved in England since the 1980s, it is uncertain if the trend has benefited all communities equally. While previous research has highlighted inequalities in CVD mortality regionally, more research on the trends among local communities is needed, in order to plan for public health interventions.
This new analysis looked at the trends in death rates from CVD for each of the 7,932 electorial wards in England (each containing an average of around 3,420 people) in England in five-year intervals between 1982 and 2006, separately for men and women aged 30-64 years and those aged 65 or over. They also examined the differences in CVD mortality across wards and the differences between the least and most deprived wards.
What did the research involve?
The researchers used data from various national databases, including the census and mortality statistics held by the Small Area Health Statistics Unit. The data on deaths from CVD, according to an agreed international classification of disease, were extracted by age, sex, year and postcode. In order to measure each ward’s socio-economic status, they used an established index of deprivation that looks at factors such as:
- income
- employment
- education
- housing
- crime
- infrastructure
The researchers put the wards into five groups (known as quintiles) according to socio-economic status, with Q1 being the least deprived and Q5 being the most. They used these groups throughout the analysis period to assess the changes in inequality in the same group of wards over time.
They used validated statistical technique to analyse CVD mortality rates in consecutive five-year intervals between 1982 and 2006. They carried out separate analyses for men and women for each period and for the ages 30-64 years and 65 years and over.
They looked both at CVD mortality and trends in CVD mortality, by comparing the CVD death rate in five-year bands, beginning when data was first available between 1982 and 1986.. Their report presents patterns of CVD mortality across wards for five bands (20 years) ending in 2002-6.
What were the basic results?
The researchers found that between 1982 and 2006, in most wards death rates from CVD declined. In 186 wards, CVD death rates had increased among women aged 65 or over. Nationally, CVD mortality declined by about two-thirds for both men and women aged 30-64, and by over a half for those aged 65 and over.
Generally, they say, the decline in death rates was proportionately larger, as would be expected, in areas that began with higher mortality (death rate).
For those aged 30-64 years, the reduction in CVD deaths varied substantially across wards – declining 4.5 times more for men and seven times more for women in the 1% of best performing wards than in the 1% of worst performing.
For those aged 65 and over, CVD mortality declined nearly five times more for men and 10 times more for women in the 1% best performing wards than in the 1% worst performing.
When they looked at the differences in the decline in death rates between the most and the least deprived wards, they found that among those aged 30-64 the differences narrowed over time, but for those aged 65 and over, the differences increased.
They say that in 2002-6, the wards with high CVD death rates fell into two groups:
- those around large metropolitan cities in northern England that started with disproportionately high rates in 1982-6 and could not ‘catch up’ despite impressive declines
- those that had started with low or average death rates in the1980s but ‘fell behind’ owing to small reductions
How did the researchers interpret the results?
Measuring local health outcomes is especially important for several reasons, say the authors. The economic downturn, rising unemployment and the austerity measures and changes in the healthcare system, may have disproportionately large effects in deprived areas and could slow down or even diminish the health gains seen in these areas, they warn.
Further improvements in CVD mortality should rely on social and economic measures as well as dietary, lifestyle and healthcare interventions, they argue, and that it is “essential to ensure that all of England’s communities receive proven interventions and are not left behind”.
Conclusion
This study provides a reliable and useful analysis of trends in CVD mortality since the 1980s, at the local level and at both younger and older ages. It has some small limitations – as the authors point out, changes in the classification of causes of death may mean that the reductions in CVD deaths and possible inequalities may be larger than estimated.
The authors say theirs is the first analysis of trends over time in CVD mortality at small-area level in England, and at both older and younger age groups. Its strength lies in its use of sophisticated modelling and mapping techniques.
However, the researchers acknowledge minor limitations with finding data for the analysis. For example, because censuses are done every 10 years, data for years in between need to be estimated indirectly, and this may introduce some error.
It is particularly hard, the researchers say, to estimate migration in and out of areas as this is not precisely known. The population level inputs into these models are estimates of death registration by place of residence for example and cannot determine whether any observed change in mortality over time is due to changes in the health of individuals as compared with changes due to differences in population composition as a result of migration.
It reveals that while most areas of England have seen a decline in death rates from cardiovascular disease, the gains have not always been shared equally and there would appear to be a strong association between social and economic deprivation and higher CVD mortality rates.
The underlying causes of these health inequalities are likely to be both complex and multifaceted, such as the negative effects of poverty on lifestyle, health behaviours and mental health.
