December 13, 2012
The number of deaths in each age and sex group for countries, regions, and the world is a critical starting point for assessing the Global Burden of Disease (GBD). A careful estimation of deaths and mortality rates by age and sex is essential to assess progress, improve health, and extend the lives of people around the world. Information about mortality rates and causes of death at different ages, especially premature mortality, is also an important impetus for public policy action.
Given the incomplete official data in most developing countries, mortality measurement requires use of multiple sources of data and a suite of statistical estimation methods. The GBD 2010 approach includes estimations of probability of under‐5 mortality, probability of adult mortality (ages 15‐59), age‐specific mortality rates, and life expectancy at different ages. In each of these estimations, the authors measured the uncertainty due to sampling error, known non‐sampling error, missing data, and model parameters. All mortality rates and estimates are reported with 95% uncertainty intervals.
Mortality rates are falling around the world. Globally, 52.8 million deaths occurred in 2010, approximately 13.5% more than in 1990 and 21.9% more than in 1970. But the global crude death rate has fallen from 11.7 to 7.7 per 1,000 population due to the much larger (86.7%) relative increase in world population – from 3.7 billion in 1970 to 6.9 billion in 2010.
The world has made tremendous progress fighting child mortality. Deaths of children under the age of 5 were cut by more than half from 16.39 million in 1970 to 11.56 million in 1990 and then to 6.84 million in 2010, although the global annual number of births increased by 12%. This progress has beaten every published prediction. However, child mortality remains a pressing issue. Effective interventions are available to prevent many of the remaining 6.8 million child deaths.
Life expectancy is increasing around the world for both men and women. Life expectancy at birth increased 11.1 years for males and 12.1 years for females from 1970 to 2010. Life expectancy at birth has risen by three to four years each decade since 1970, except for the 1990s. The slowdown in global progress in the 1990s was driven by increases in mortality in eastern and southern sub‐Saharan Africa from the HIV epidemic and alcohol-related increases in eastern Europe and central Asia.
The average age of death is a measure of both the aging of the world’s population and the decline in death rates at younger ages; it summarizes the demographic progress in a country. Average age at death has risen in all regions since 1970, in some cases by 0.7 years per calendar year. Around the world, including in regions most affected by HIV/AIDS, there has also been an increase in the mean age of death, with the most dramatic increases in east Asia, south Asia, southeast Asia, and all of Latin America. The very substantial progress over the last 40 years in postponing mortality in populations in all regions means that more people are dying at the oldest age groups. Deaths at ages above 80 increased from 3.84 million in 1970 to 12.11 million in 2010, or by more than 210%. The percentage increase in deaths at ages 70 to 74 and 75 to 79 was 63.6% and 96.1% respectively, confirming this marked mortality transition worldwide.
A troubling mortality trend is among young adults, especially young men, who are now dying at very high rates in eastern Europe, central Asia, and eastern and southern Africa. This is largely due to the epidemics of alcohol‐related mortality and HIV/AIDS, respectively. The average mortality rates among males aged 25 to 39 fell by little more than 19.7% over the four decades as compared to much higher declines in other age‐groups. Due to demographic change and increases in death rates, the numbers of young adult deaths at 15 to 49 years in Zambia, Zimbabwe, South Africa, and Botswana has increased by well over 500% since 1970, mostly due to rapid increases in mortality from HIV/AIDS. In countries such as Venezuela, Honduras, Qatar, United Arab Emirates, and Paraguay, deaths in young adults have increased by more than 100%.
Continued effort is required to sustain and accelerate the progress in reducing child mortality to decrease the 6.8 million child deaths in the world. Global public health policy for several decades has focused on improving child survival. With substantial progress made in most regions, focused development assistance is needed for those countries that are still experiencing high rates of child mortality, particularly in northern and central sub-Saharan Africa. The systematic tendency to underestimate progress in child mortality suggests that we will have made greater progress on Millennium Development Goal 4 by 2015 than what will be estimated.
As more and more children survive to adulthood, efforts must also be intensified to prevent young adult deaths. In most developed and some developing countries, deaths at ages 15 to 49 have decreased, despite substantial growth in population at these ages. Other countries have seen moderate increases, while others – particularly in sub‐Saharan Africa – have seen extreme increases of over 500% since 1970 with the growing prevalence of HIV/AIDS.
The pace of demographic change as reflected in the mean age of death is dramatic in many regions of the world. Higher average ages of death also mean higher average ages of individuals seeking medical care. Health systems need to adapt to the rapid change in population needs. The speed of the demographic transformation alone poses challenges for systems to adjust their health workforce, infrastructure, and service provision.
Our knowledge about global, regional, and national mortality changes will only be reliably informed if greater attention is paid to strengthening information gathering systems – like civil registration – in developing countries. The recent global focus on civil registration and vital statistics is a very welcomed initiative, but it needs to be sustained and expanded if we are to more confidently track global health progress. Timely reporting of mortality is critical if the data are to be truly useful for policymakers.
Wang H*, Dwyer-Lindgren L, Lofgren KT, Rajaratnam JK, Marcus JR, Levin-Rector A, Levitz C, Lopez AD, Murray CJL. Age-specific and sex-specific mortality in 187 countries, 1970–2010: a systematic analysis for the Global Burden of Disease Study 2010. The Lancet. 2012 Dec 13; 380: 2071–2094.