Global, regional, and national age-sex-specific mortality and life expectancy, 1950-2017: a systematic analysis for the Global Burden of Disease Study 2017.
Background Assessments of age-specific mortality and life expectancy have been done by the UN Population Division,
Department of Economics and Social Affairs (UNPOP), the United States Census Bureau, WHO, and as part of
previous iterations of the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD). Previous iterations of
the GBD used population estimates from UNPOP, which were not derived in a way that was internally consistent
with the estimates of the numbers of deaths in the GBD. The present iteration of the GBD, GBD 2017, improves on
previous assessments and provides timely estimates of the mortality experience of populations globally.
Methods The GBD uses all available data to produce estimates of mortality rates between 1950 and 2017 for 23 age
groups, both sexes, and 918 locations, including 195 countries and territories and subnational locations for
16 countries. Data used include vital registration systems, sample registration systems, household surveys (complete
birth histories, summary birth histories, sibling histories), censuses (summary birth histories, household deaths),
and Demographic Surveillance Sites. In total, this analysis used 8259 data sources. Estimates of the probability of
death between birth and the age of 5 years and between ages 15 and 60 years are generated and then input into a
model life table system to produce complete life tables for all locations and years. Fatal discontinuities and mortality
due to HIV/AIDS are analysed separately and then incorporated into the estimation. We analyse the relationship
between age-specific mortality and development status using the Socio-demographic Index, a composite measure
based on fertility under the age of 25 years, education, and income. There are four main methodological
improvements in GBD 2017 compared with GBD 2016: 622 additional data sources have been incorporated; new
estimates of population, generated by the GBD study, are used; statistical methods used in different components of
the analysis have been further standardised and improved; and the analysis has been extended backwards in time by
two decades to start in 1950.
Findings Globally, 18·7% (95% uncertainty interval 18·4–19·0) of deaths were registered in 1950 and that proportion
has been steadily increasing since, with 58·8% (58·2–59·3) of all deaths being registered in 2015. At the global level,
between 1950 and 2017, life expectancy increased from 48·1 years (46·5–49·6) to 70·5 years (70·1–70·8) for men
and from 52·9 years (51·7–54·0) to 75·6 years (75·3–75·9) for women. Despite this overall progress, there remains
substantial variation in life expectancy at birth in 2017, which ranges from 49·1 years (46·5–51·7) for men in the
Central African Republic to 87·6 years (86·9–88·1) among women in Singapore. The greatest progress across age
groups was for children younger than 5 years; under-5 mortality dropped from 216·0 deaths (196·3–238·1) per
1000 livebirths in 1950 to 38·9 deaths (35·6–42·83) per 1000 livebirths in 2017, with huge reductions across
countries. Nevertheless, there were still 5·4 million (5·2–5·6) deaths among children younger than 5 years in the
world in 2017. Progress has been less pronounced and more variable for adults, especially for adult males, who had
stagnant or increasing mortality rates in several countries. The gap between male and female life expectancy between
1950 and 2017, while relatively stable at the global level, shows distinctive patterns across super-regions and has
consistently been the largest in central Europe, eastern Europe, and central Asia, and smallest in south Asia.
Performance was also variable across countries and time in observed mortality rates compared with those expected
on the basis of development.
Interpretation This analysis of age-sex-specific mortality shows that there are remarkably complex patterns in
population mortality across countries. The findings of this study highlight global successes, such as the large decline
in under-5 mortality, which reflects significant local, national, and global commitment and investment over several
decades. However, they also bring attention to mortality patterns that are a cause for concern, particularly among
adult men and, to a lesser extent, women, whose mortality rates have stagnated in many countries over the time
period of this study, and in some cases are increasing.