Mortality from ischaemic heart disease by country, region, and age: statistics from World Health Organisation and United Nations

Abstract

Background: Ischaemic heart disease (IHD) is the leading cause of death worldwide. The World Health Organisation (WHO) collects mortality data coded using the International Statistical Classification of Diseases (ICD) code.

Methods: We analysed IHD deaths world-wide between 1995 and 2009 and used the UN population database to calculate age-specific and directly and indirectly age-standardised IHD mortality rates by country and region.

Results: IHD is the single largest cause of death worldwide, causing 7,249,000 deaths in 2008, 12.7% of total global mortality. There is more than 20-fold variation in IHD mortality rates between countries. Highest IHD mortality rates are in Eastern Europe and Central Asian countries; lowest rates in high income countries. For the working-age population, IHD mortality rates are markedly higher in low-and-middle income countries than in high income countries. Over the last 25 years, age-standardised IHD mortality has fallen by more than half in high income countries, but the trend is flat or increasing in some low-and-middle income countries. Low-and-middle income countries now account for more than 80% of global IHD deaths.

Conclusions: The global burden of IHD deaths has shifted to low-and-middle income countries as lifestyles approach those of high income countries. In high income countries, population ageing maintains IHD as the leading cause of death. Nevertheless, the progressive decline in age-standardised IHD mortality in high income countries shows that increasing IHD mortality is not inevitable. The 20-fold mortality difference between countries, and the temporal trends, may hold vital clues for handling IHD epidemic which is migratory, and still burgeoning.

Keywords: Coronary heart disease; Ischaemic heart disease; Mortality; Trends.

Fig. 1

(a) A standard population of 2000 people, distributed equally amongst "young" (under 60 years) and "old" (60 years and older) groups which have different death rates. This distribution of ages will be used as the "standard" in the other panels. (b) A country with the same age-specific risks, but whose population is older. Crude death rate is higher because a greater proportion of people are in the high-risk age group. However, age-standardisation prevents the ageing artefact by reconstituting a population of the "standard" age distribution, to obtain the same standardised death rate as (a). (c) A country which, compared with (a), has double the death rate at each age group. Crude death rates, and age-standardised death rates are doubled (d) A country with double the age-specific mortality and an older population. Crude mortality is very much higher but age-standardised mortality, which reconstitutes a standard distribution of ages, is only twice that of panel (a).

Fig. 2

If a country reports age-specific population but only total IHD deaths (without an age breakdown), it is not possible to calculate directly standardised mortality rates. Instead, by making the assumption that the age relationship of mortality is a scaled-up or scaled-down version of that of a standard population, it is possible to calculate an indirectly standardised mortality ratio expressing the country's mortality relative to that of the standard population. Panels (b), (c) and (d) calculate the indirectly standardised mortality ratio for the same country data as the corresponding panels in Figure 1, but with the age breakdown of deaths concealed.

Fig. 3

Change in mortality with age in UK, USA, Japan and France.

Fig. 4

IHD mortality by population age group for selected countries. Age-specific mortality rate for selected countries. The most recent year of available data between 2005 and 2009 is displayed.

Fig. 5

(a). Changes in crude annual mortality rates from ischaemic heart disease for selected Countries between 2000 and 2009. (b). Changes in directly standardised annual mortality rates from ischaemic heart disease for selected Countries between 2000 and 2009.