Global, regional, and national comparative risk assessment of 84
                behavioural, environmental and occupational, and metabolic risks
                or clusters of risks, 1990-2016: a systematic analysis for the
                Global Burden of Disease Study 2016

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