Summary
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 acro...
