Physicians' Academy for Cardiovascular Education

Worldwide decreasing trends in age-specific death rates opposed by population aging and growth

Literature - Roth GA et al., NEJM 2015

Demographic and Epidemiologic Drivers of Global Cardiovascular Mortality

 
Roth GA, Forouzanfar MH, Moran AE et al.,
N Engl J Med 2015; 372:1333-1341 April 2, 2015 DOI: 10.1056/NEJMoa1406656
 

Background

As a consequence of population growth, aging of populations and epidemiological changes in cardiovascular (CV) disease, mortality from CV and circulatory disease are increasing [1]. For prevention strategy and policy reasons, it is important to disentangle the drivers of the observed global trends in mortality.
The Global Burden of Disease Study 2013 (GBD 2013) estimated age-specific CV mortality using standardised methods in 188 countries, from 1990 until 2013 [2]. This study examined the separate contribution of three causes of change in CV mortality rate: namely change in population size, aging of the population and changes in age-specific CV death rates. Furthermore, the relationship between changes in CV mortality due to age-specific death rates and changes in gross domestic product (GDP) per capita was examined. This is of specific interest for developing nations, since economic growth has been blamed for epidemiological changes in CV mortality.
 

Main results

  • An increase (40.8%, 95% Uncertainty Interval (UI): 33.6-44.1) in the number of people who died from CV disease was seen in 2013 (over 17.3 million, 95%UI: 16.5-18.1) as compared with 1990 (>12 million per year).
  • Over the same period, a decrease of 39.3% (95%UI: 33.6-44.1) in deaths attributable to epidemiological changes was seen.
  • The increase in mortality was driven by the change since 1990 in the number of deaths attributed to population aging (55% increase, 95%UI: 54.5-55.4) and population growth (25.1% increase, 95%UI: 24.7-25.5).
  • This pattern in changes in the number of deaths due to different reasons was also seen for most specific CV causes of death, with ischaemic heart disease as the largest contributor to the increase of CV deaths, despite an estimated decline of 34.4% owing to global epidemiological changes.
  • The change in total number of deaths, over the evaluated period varied substantially by geographical region. South Asia showed the largest estimated increase in deaths from CV disease (97.4%, 95%UI: 72-126.1). Only Central Europe and Western Europe showed significant declines in the number of deaths over this period (5.2% and 12.8% respectively).
  • Southern Latin America, Australasia and high-income North America had no net change in the number of deaths because population aging and growth balanced out declines in age-specific death rates.
  • National income per capita and contribution of age-specific death rate to CV mortality was only significantly correlated in countries with upper-middle income (Pearsons’s correlation coefficient r=-0.33, P=0.02, and Spearman’s rho : =-0.37, P=0.006).

Conclusion

Global trends in CV mortality are a consequence of the combined effect of population growth, population aging and changing age-specific death rates. These analyses give insight in to which extent population aging and growth have counterbalanced reductions in CV mortality. Some regions, mostly high-income countries, show a reduction in CV death due to epidemiologic change. In contrast, in a few regions a rise in CV deaths is observed as a consequence of population growth and aging without a clear decline in CV deaths due to epidemiological change.
This analysis shows that epidemiologic change would have led to lower CV mortality in most regions, but population growth and aging counteract this trend in some regions. It seems unlikely that economic growth alone will address a countries’ burden of CV disease.
 
Find this article online at New England Journal of Medicine
 

References

1. Lozano R, Naghavi M, Foreman K, et al. Global and regional mortality from 235 causes of death for 20 age groups in 1990 and 2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet 2012; 380: 2095-128.
2. GBD 2013 Mortality and Causes of Death Collaborators. Global, regional, and national age-sex  specific all-cause and cause-specific mortality for 240 causes of death, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet 2014; 385: 117-71.

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