Heart disease and stroke kill most, but in some countries cancer has overtaken them

Getting to the heart of the matter. Gertjan Zeeman, CC BY-NC-SA

Cardiovascular disease, which includes heart disease and stroke, is the biggest killer in Europe. However, a study published in European Heart Journal shows how different the picture can look across individual countries.

The study, compiled using two sets of data from the WHO and the OECD, suggests that although cardiovascular disease (CVD) causes twice as many deaths as cancer in some countries, in ten others – Belgium, Denmark, France, Luxembourg, The Netherlands, Portugal, Slovenia, Spain and San Marino, and Israel, which is included in the data – cancer has now overtaken it as the leading cause of death in men. Denmark has also become the first country where cancer has overtaken CVD as the leading cause of death in women.

The study may suggest – as Nick Townsend, one of authors does – that improvements in known risk factors such as smoking are making a difference, as is treatment. Fewer people are developing CVD in some countries, Townsend says, and when they do, fewer are dying.

Single and shared risk factors

Risk factors are complex, and some can be considered shared. Age, for example, will be a shared risk factor for both CVD and cancer, as could obesity, smoking, alcohol, and physical activity, and they must be continuously targeted to minimise their effects on CVD and cancer. Others can be considered non-shared, such as mental state, certain environmental chemicals or the environment inside a house. Taking this into account, a reduction in cardiovascular deaths but an increase of cancer deaths when the overall death rate has remained stable might indicate a small success in reducing some non-shared risk factors but not shared risk factors, which will still need to be addressed.

Looking more widely at the overall death rates for each country in 2014, Singapore appears to have the lowest overall death rate among the developed countries, being ranked 217th (out of 225). Germany, on the other hand is ranked 31st worst, which indicates that it has the highest overall death rate among the developed countries. The UK is doing better, ranked 59th. However, if we look back over the last a few years, Singapore’s overall death rate has been rising while in Germany and the UK these have remained stable. In northern Europe, Iceland, Sweden and Finland have also had stable overall death rates while Norway and Denmark have seen an overall decline.

A declining overall death rate could mean all-round success in reducing shared risk factors for many human diseases (as well as improved treatments and rehabilitation). But why would cancer deaths outnumber CVD deaths in Denmark? Three possible explanations might be that there are still some remaining high risk factors for cancer that are not shared with CVD, for example infections or radiation; better treatments and rehabilitation for CVD rather than cancer; or a delay in age at the onset of CVD, but not necessarily cancer.

The third age

Humans are now entering something called the third epidemiological transition, a period characterised by a delay in the age at which we develop chronic diseases. Looking at world incidence studies (the number of new cases each year), this is most apparent in developed countries, while developing countries, such as China, have been catching up.

This can also impact a country from an economic point of view. A recent Korean study revealed the lifetime economic burden of stroke according to the age at onset. Obviously, a greater burden was seen in patients with early disease events, and is likely to also be greater in relatively less wealthy countries. In other words, the economic burden due to human disease can widen the wealth gap across countries.

Accurate monitoring

Trends of disease incidence (the number of new cases each year), prevalence (existing cases each year), admissions (number of occasions/events admitted to hospitals), and deaths over years can vary across countries around the world. The driving forces behind different diseases can also vary depending on the magnitude of risk and protective effects of various things like the environment (including natural, physical, social, psychological, and improved treatments and rehabilitation) and/or genetic.

When it comes to monitoring disease onset, the scientific literature is still very limited and we need to more regular and systematic monitoring. This is also the case for records in general, in databases from WHO and OECD – some countries might have data up to 2011 while some only until 1998. Resources aren’t just about treating and preventing, but recording too.

We need to examine changes of disease events and death rates on a regular basis. We also need to keep monitoring the changes of risk factors and the age at onset that could explain the changes of disease events and death rates. These would help direct how medical and social resources are allocated locally, nationally and globally over time.