Abstract:
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BACKGROUND: The Global Burden of Diseases, Injuries, and Risk
Factors Study 2016 (GBD 2016) provides a comprehensive
assessment of risk factor exposure and attributable burden of
disease. By providing estimates over a long time series, this
study can monitor risk exposure trends critical to health
surveillance and inform policy debates on the importance of
addressing risks in context. METHODS: We used the comparative
risk assessment framework developed for previous iterations of
GBD to estimate levels and trends in exposure, attributable
deaths, and attributable disability-adjusted life-years (DALYs),
by age group, sex, year, and location for 84 behavioural,
environmental and occupational, and metabolic risks or clusters
of risks from 1990 to 2016. This study included 481 risk-outcome
pairs that met the GBD study criteria for convincing or probable
evidence of causation. We extracted relative risk (RR) and
exposure estimates from 22 717 randomised controlled trials,
cohorts, pooled cohorts, household surveys, census data,
satellite data, and other sources, according to the GBD 2016
source counting methods. Using the counterfactual scenario of
theoretical minimum risk exposure level (TMREL), we estimated
the portion of deaths and DALYs that could be attributed to a
given risk. Finally, we explored four drivers of trends in
attributable burden: population growth, population ageing,
trends in risk exposure, and all other factors combined.
FINDINGS: Since 1990, exposure increased significantly for 30
risks, did not change significantly for four risks, and
decreased significantly for 31 risks. Among risks that are
leading causes of burden of disease, child growth failure and
household air pollution showed the most significant declines,
while metabolic risks, such as body-mass index and high fasting
plasma glucose, showed significant increases. In 2016, at Level
3 of the hierarchy, the three leading risk factors in terms of
attributable DALYs at the global level for men were smoking
(124.1 million DALYs [95% UI 111.2 million to 137.0 million]),
high systolic blood pressure (122.2 million DALYs [110.3 million
to 133.3 million], and low birthweight and short gestation (83.0
million DALYs [78.3 million to 87.7 million]), and for women,
were high systolic blood pressure (89.9 million DALYs [80.9
million to 98.2 million]), high body-mass index (64.8 million
DALYs [44.4 million to 87.6 million]), and high fasting plasma
glucose (63.8 million DALYs [53.2 million to 76.3 million]). In
2016 in 113 countries, the leading risk factor in terms of
attributable DALYs was a metabolic risk factor. Smoking remained
among the leading five risk factors for DALYs for 109 countries,
while low birthweight and short gestation was the leading risk
factor for DALYs in 38 countries, particularly in sub-Saharan
Africa and South Asia. In terms of important drivers of change
in trends of burden attributable to risk factors, between 2006
and 2016 exposure to risks explains an 9.3% (6.9-11.6) decline
in deaths and a 10.8% (8.3-13.1) decrease in DALYs at the global
level, while population ageing accounts for 14.9% (12.7-17.5) of
deaths and 6.2% (3.9-8.7) of DALYs, and population growth for
12.4% (10.1-14.9) of deaths and 12.4% (10.1-14.9) of DALYs. The
largest contribution of trends in risk exposure to disease
burden is seen between ages 1 year and 4 years, where a decline
of 27.3% (24.9-29.7) of the change in DALYs between 2006 and
2016 can be attributed to declines in exposure to risks.
INTERPRETATION: Increasingly detailed understanding of the
trends in risk exposure and the RRs for each risk-outcome pair
provide insights into both the magnitude of health loss
attributable to risks and how modification of risk exposure has
contributed to health trends. Metabolic risks warrant particular
policy attention, due to their large contribution to global
disease burden, increasing trends, and variable patterns across
countries at the same level of development. GBD 2016 findings
show that, while it has huge potential to improve health, risk
modification has played a relatively small part in the past
decade. FUNDING: The Bill & Melinda Gates Foundation,
Bloomberg Philanthropies. |