Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015

Abstract

Background: The Global Burden of Diseases, Injuries, and Risk Factors Study 2015 provides an up-to-date synthesis of the evidence for risk factor exposure and the attributable burden of disease. By providing national and subnational assessments spanning the past 25 years, this study can inform debates on the importance of addressing risks in context.

Methods: We used the comparative risk assessment framework developed for previous iterations of the Global Burden of Disease Study to estimate attributable deaths, disability-adjusted life-years (DALYs), and trends in exposure by age group, sex, year, and geography for 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks from 1990 to 2015. This study included 388 risk-outcome pairs that met World Cancer Research Fund-defined criteria for convincing or probable evidence. We extracted relative risk and exposure estimates from randomised controlled trials, cohorts, pooled cohorts, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. We developed a metric that allows comparisons of exposure across risk factors-the summary exposure value. Using the counterfactual scenario of theoretical minimum risk level, we estimated the portion of deaths and DALYs that could be attributed to a given risk. We decomposed trends in attributable burden into contributions from population growth, population age structure, risk exposure, and risk-deleted cause-specific DALY rates. We characterised risk exposure in relation to a Socio-demographic Index (SDI).

Findings: Between 1990 and 2015, global exposure to unsafe sanitation, household air pollution, childhood underweight, childhood stunting, and smoking each decreased by more than 25%. Global exposure for several occupational risks, high body-mass index (BMI), and drug use increased by more than 25% over the same period. All risks jointly evaluated in 2015 accounted for 57·8% (95% CI 56·6-58·8) of global deaths and 41·2% (39·8-42·8) of DALYs. In 2015, the ten largest contributors to global DALYs among Level 3 risks were high systolic blood pressure (211·8 million [192·7 million to 231·1 million] global DALYs), smoking (148·6 million [134·2 million to 163·1 million]), high fasting plasma glucose (143·1 million [125·1 million to 163·5 million]), high BMI (120·1 million [83·8 million to 158·4 million]), childhood undernutrition (113·3 million [103·9 million to 123·4 million]), ambient particulate matter (103·1 million [90·8 million to 115·1 million]), high total cholesterol (88·7 million [74·6 million to 105·7 million]), household air pollution (85·6 million [66·7 million to 106·1 million]), alcohol use (85·0 million [77·2 million to 93·0 million]), and diets high in sodium (83·0 million [49·3 million to 127·5 million]). From 1990 to 2015, attributable DALYs declined for micronutrient deficiencies, childhood undernutrition, unsafe sanitation and water, and household air pollution; reductions in risk-deleted DALY rates rather than reductions in exposure drove these declines. Rising exposure contributed to notable increases in attributable DALYs from high BMI, high fasting plasma glucose, occupational carcinogens, and drug use. Environmental risks and childhood undernutrition declined steadily with SDI; low physical activity, high BMI, and high fasting plasma glucose increased with SDI. In 119 countries, metabolic risks, such as high BMI and fasting plasma glucose, contributed the most attributable DALYs in 2015. Regionally, smoking still ranked among the leading five risk factors for attributable DALYs in 109 countries; childhood underweight and unsafe sex remained primary drivers of early death and disability in much of sub-Saharan Africa.

Interpretation: Declines in some key environmental risks have contributed to declines in critical infectious diseases. Some risks appear to be invariant to SDI. Increasing risks, including high BMI, high fasting plasma glucose, drug use, and some occupational exposures, contribute to rising burden from some conditions, but also provide opportunities for intervention. Some highly preventable risks, such as smoking, remain major causes of attributable DALYs, even as exposure is declining. Public policy makers need to pay attention to the risks that are increasingly major contributors to global burden.

Funding: Bill & Melinda Gates Foundation.

Figure 1

Global proportion of all-cause DALYs attributable to behavioural, environmental and occupational, and metabolic risk factors and their overlaps by region for both sexes combined in 2015 Locations are reported in order of total all-cause DALYs population attributable fraction. DALYs=disability-adjusted life-years. ∩=interaction.

Figure 2

Global DALYs attributable to Level 2 risk factors for (A) men and (B) women in 2015 DALYs=disability-adjusted life-years.

Figure 3

Leading 30 Level 3 global risk factors for DALYs for both sexes combined, 1990, 2005, and 2015, with percentage change in number of DALYs, and all-age, and age-standardised rates Risks are connected by lines between time periods. For the time period of 1990 to 2005 and for 2005 to 2015, three measures of change are shown: percent change in the number of DALYs, percent change in the all-age DALY rate, and percent change in the age-standardised DALY rate. Changes that are statistically significant are shown in bold. DALYs=disability-adjusted life-years.

Figure 4

Global attributable DALYs in 2015 for each Level 3 risk factor versus percentage change in SEV from 1990 to 2015 for both sexes combined Risks with 100 000 DALYs or more are presented. DALYs are represented on a logarithmic scale. We have excluded occupational exposure to benzene, diesel engine exhaust, and occupational exposure to silica, which all had SEV increases of greater than 50%. Ambient PM=ambient particulate matter pollution. Arsenic=occupational exposure to arsenic. Asbestos=occupational exposure to asbestos. Asthmagens=occupational asthmagens. Beryllium=occupational exposure to beryllium. BMD=low bone mineral density. BMI=high body-mass index. Cadmium=occupational exposure to cadmium. Calcium=diet low in calcium. Cholesterol=high total cholesterol. Chromium=occupational exposure to chromium. DALYs=disability-adjusted life-years. Ergonomic=occupational ergonomic factors. Fibre=diet low in fibre. Formaldehyde=occupational exposure to formaldehyde. FPG=high fasting plasma glucose. Fruits=diet low in fruits. GFR=low glomerular filtration rate. Handwashing=no handwashing with soap. Household air=household air pollution. IPV=intimate partner violence. Lead=lead exposure. Milk=diet low in milk. Nickel=occupational exposure to nickel. Noise=occupational noise. Nuts and seeds=diet low in nuts and seeds. Occupational SHS=occupational exposure to second-hand smoke. Omega-3=diet low in seafood omega-3 fatty acids. Ozone=ambient ozone pollution. PAH=occupational exposure to polycyclic aromatic hydrocarbons. Physical activity=low physical activity. PM, gases, and fumes=occupational particulate matter, gases, and fumes. Processed meat=diet high in processed meat. PUFA=diet low in polyunsaturated fatty acids. Radon=residential radon. Red meat=diet high in red meat. Sanitation=unsafe sanitation. SBP=high systolic blood pressure. SEV=summary exposure value. SHS=second-hand smoke. Sodium=diet high in sodium. Sugar-sweetened beverages=diet high in sugar-sweetened beverages. Sulphuric acid=occupational exposure to sulphuric acid. Stunting=childhood stunting. Trans fatty acids=diet high in trans fatty acids. Trichloroethylene=occupational exposure to trichloroethylene. Underweight=childhood underweight. Vegetables=diet low in vegetables. Wasting=childhood wasting. Water=unsafe water. Whole grains=diet low in whole grains.

Figure 5

Global decomposition of changes in all-cause DALYs attributable to Level 3 risk factors from 1990 to 2015 Risks are reported in order of percentage change in the number of attributable DALYs from 1990 to 2015. We excluded DALYs attributable to unsafe sex because this risk factor is not estimated on the basis of exposure and relative risk. Changes due to population growth, population ageing, risk exposure, and the risk-deleted DALY rate are shown. DALYs=disability-adjusted life-years.

Figure 6

Coevolution of SEV and SDI for the top ten global risks in terms of attributable disability-adjusted life-years in 2015 Coloured points show SEVs for Global Burden of Disease regions. Each point represents 1 year in 5 year intervals from 1990 to 2015. The solid black line represents the expected SEV on the basis of SDI alone. SDI=Socio-demographic Index. SEV=summary exposure values.

Figure 7

Leading ten Level 3 risk factors in terms of disability-adjusted life-years for both sexes combined in 2015, by location The 15 leading risk factors are coloured. Bone mineral density=low bone mineral density. Handwashing=no handwashing with soap. Int partner violence=intimate partner violence. Nuts and seeds=diet low in nuts and seeds. Occ=occupational. Particulate matter=ambient particulate matter pollution. Physical activity=low physical activity. Processed meat=diet high in processed meat. SDI=Socio-demographic Index. Subopt=suboptimal. Sweetened beverages=diet high in sugar-sweetened beverages. Vegetables=diet low in vegetables.

Figure 7

Leading ten Level 3 risk factors in terms of disability-adjusted life-years for both sexes combined in 2015, by location The 15 leading risk factors are coloured. Bone mineral density=low bone mineral density. Handwashing=no handwashing with soap. Int partner violence=intimate partner violence. Nuts and seeds=diet low in nuts and seeds. Occ=occupational. Particulate matter=ambient particulate matter pollution. Physical activity=low physical activity. Processed meat=diet high in processed meat. SDI=Socio-demographic Index. Subopt=suboptimal. Sweetened beverages=diet high in sugar-sweetened beverages. Vegetables=diet low in vegetables.

Figure 7

Leading ten Level 3 risk factors in terms of disability-adjusted life-years for both sexes combined in 2015, by location The 15 leading risk factors are coloured. Bone mineral density=low bone mineral density. Handwashing=no handwashing with soap. Int partner violence=intimate partner violence. Nuts and seeds=diet low in nuts and seeds. Occ=occupational. Particulate matter=ambient particulate matter pollution. Physical activity=low physical activity. Processed meat=diet high in processed meat. SDI=Socio-demographic Index. Subopt=suboptimal. Sweetened beverages=diet high in sugar-sweetened beverages. Vegetables=diet low in vegetables.

Figure 7

Leading ten Level 3 risk factors in terms of disability-adjusted life-years for both sexes combined in 2015, by location The 15 leading risk factors are coloured. Bone mineral density=low bone mineral density. Handwashing=no handwashing with soap. Int partner violence=intimate partner violence. Nuts and seeds=diet low in nuts and seeds. Occ=occupational. Particulate matter=ambient particulate matter pollution. Physical activity=low physical activity. Processed meat=diet high in processed meat. SDI=Socio-demographic Index. Subopt=suboptimal. Sweetened beverages=diet high in sugar-sweetened beverages. Vegetables=diet low in vegetables.

Figure 7

Leading ten Level 3 risk factors in terms of disability-adjusted life-years for both sexes combined in 2015, by location The 15 leading risk factors are coloured. Bone mineral density=low bone mineral density. Handwashing=no handwashing with soap. Int partner violence=intimate partner violence. Nuts and seeds=diet low in nuts and seeds. Occ=occupational. Particulate matter=ambient particulate matter pollution. Physical activity=low physical activity. Processed meat=diet high in processed meat. SDI=Socio-demographic Index. Subopt=suboptimal. Sweetened beverages=diet high in sugar-sweetened beverages. Vegetables=diet low in vegetables.

Figure 7

Leading ten Level 3 risk factors in terms of disability-adjusted life-years for both sexes combined in 2015, by location The 15 leading risk factors are coloured. Bone mineral density=low bone mineral density. Handwashing=no handwashing with soap. Int partner violence=intimate partner violence. Nuts and seeds=diet low in nuts and seeds. Occ=occupational. Particulate matter=ambient particulate matter pollution. Physical activity=low physical activity. Processed meat=diet high in processed meat. SDI=Socio-demographic Index. Subopt=suboptimal. Sweetened beverages=diet high in sugar-sweetened beverages. Vegetables=diet low in vegetables.

Figure 7

Leading ten Level 3 risk factors in terms of disability-adjusted life-years for both sexes combined in 2015, by location The 15 leading risk factors are coloured. Bone mineral density=low bone mineral density. Handwashing=no handwashing with soap. Int partner violence=intimate partner violence. Nuts and seeds=diet low in nuts and seeds. Occ=occupational. Particulate matter=ambient particulate matter pollution. Physical activity=low physical activity. Processed meat=diet high in processed meat. SDI=Socio-demographic Index. Subopt=suboptimal. Sweetened beverages=diet high in sugar-sweetened beverages. Vegetables=diet low in vegetables.