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

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.

Global mortality, disability, and the contribution of risk factors: Global Burden of Disease Study

BACKGROUND

Prevention and control of disease and injury require information about the leading medical causes of illness and exposures or risk factors. The assessment of the public-health importance of these has been hampered by the lack of common methods to investigate the overall, worldwide burden. The Global Burden of Disease Study (GBD) provides a standardised approach to epidemiological assessment and uses a standard unit, the disability-adjusted life year (DALY), to aid comparisons.

METHODS

DALYs for each age-sex group in each GBD region for 107 disorders were calculated, based on the estimates of mortality by cause, incidence, average age of onset, duration, and disability severity. Estimates of the burden and prevalence of exposure in different regions of disorders attributable to malnutrition, poor water supply, sanitation and personal and domestic hygiene, unsafe sex, tobacco use, alcohol, occupation, hypertension, physical inactivity, use of illicit drugs, and air pollution were developed.

FINDINGS

Developed regions account for 11.6% of the worldwide burden from all causes of death and disability, and account for 90.2% of health expenditure worldwide. Communicable, maternal, perinatal, and nutritional disorders explain 43.9%; non-communicable causes 40.9%; injuries 15.1%; malignant neoplasms 5.1%; neuropsychiatric conditions 10.5%; and cardiovascular conditions 9.7% of DALYs worldwide. The ten leading specific causes of global DALYs are, in descending order, lower respiratory infections, diarrhoeal diseases, perinatal disorders, unipolar major depression, ischaemic heart disease, cerebrovascular disease, tuberculosis, measles, road-traffic accidents, and congenital anomalies. 15.9% of DALYs worldwide are attributable to childhood malnutrition and 6.8% to poor water, and sanitation and personal and domestic hygiene.

INTERPRETATION

The three leading contributors to the burden of disease are communicable and perinatal disorders affecting children. The substantial burdens of neuropsychiatric disorders and injuries are under-recognised. The epidemiological transition in terms of DALYs has progressed substantially in China, Latin America and the Caribbean, other Asia and islands, and the middle eastern crescent. If the burdens of disability and death are taken into account, our list differs substantially from other lists of the leading causes of death. DALYs provide a common metric to aid meaningful comparison of the burden of risk factors, diseases, and injuries.

Natural history of liver fibrosis progression in patients with chronic hepatitis C. The OBSVIRC, METAVIR, CLINIVIR, and DOSVIRC groups

BACKGROUND

Our aim was to assess the natural history of liver fibrosis progression in hepatitis C and the factors associated with this progression.

METHODS

We recruited 2235 patients from the Observatoire de l'Hépatite C (OBSVIRC) population, the Cohorte Hépatite C Pitié-Salpétrière (DOSVIRC) population, and the original METAVIR population. All the patients had a biopsy sample compatible with chronic hepatitis C as assessed by the METAVIR scoring system (grades the stage of fibrosis on a five-point scale, F0 = no fibrosis, F4 = cirrhosis, and histological activity on a four-point scale, A0 = no activity, A3 = severe activity). No patient had received interferon treatment before the liver biopsy sample was obtained. We assessed the effect of nine factors on fibrosis progression: age at biopsy; estimated duration of infection; sex; age at infection; alcohol consumption; hepatitis C virus C (HCV) genotype; HCV viraemia; cause of infection; and histological activity grade. We defined fibrosis progression per year as the ratio between fibrosis stage in METAVIR units and the duration of infection (1 unit = one stage, 4 units = cirrhosis).

FINDINGS

The median rate of fibrosis progression per year was 0.133 fibrosis unit (95% CI 0.125-0.143), which was similar to the estimates from previous studies (0.146 to 0.154). Three independent factors were associated with an increased rate of fibrosis progression: age at infection older than 40 years, daily alcohol consumption of 50 g or more, and male sex. There was no association between fibrosis progression and HCV genotype. The median estimated duration of infection for progression to cirrhosis was 30 years (28-32), ranging from 13 years in men infected after the age of 40 to 42 years in women who did not drink alcohol and were infected before the age of 40. Without treatment, 377 (33%) patients had an expected median time to cirrhosis of less than 20 years, and 356 (31%) will never progress to cirrhosis or will not progress for at least 50 years.

INTERPRETATION

The host factors of ageing, alcohol consumption, and male sex have a stronger association with fibrosis progression than virological factors in HCV infection.

Alcohol use and burden for 195 countries and territories, 1990-2016: a systematic analysis for the Global Burden of Disease Study 2016

BACKGROUND

Alcohol use is a leading risk factor for death and disability, but its overall association with health remains complex given the possible protective effects of moderate alcohol consumption on some conditions. With our comprehensive approach to health accounting within the Global Burden of Diseases, Injuries, and Risk Factors Study 2016, we generated improved estimates of alcohol use and alcohol-attributable deaths and disability-adjusted life-years (DALYs) for 195 locations from 1990 to 2016, for both sexes and for 5-year age groups between the ages of 15 years and 95 years and older.

METHODS

Using 694 data sources of individual and population-level alcohol consumption, along with 592 prospective and retrospective studies on the risk of alcohol use, we produced estimates of the prevalence of current drinking, abstention, the distribution of alcohol consumption among current drinkers in standard drinks daily (defined as 10 g of pure ethyl alcohol), and alcohol-attributable deaths and DALYs. We made several methodological improvements compared with previous estimates: first, we adjusted alcohol sales estimates to take into account tourist and unrecorded consumption; second, we did a new meta-analysis of relative risks for 23 health outcomes associated with alcohol use; and third, we developed a new method to quantify the level of alcohol consumption that minimises the overall risk to individual health.

FINDINGS

Globally, alcohol use was the seventh leading risk factor for both deaths and DALYs in 2016, accounting for 2·2% (95% uncertainty interval [UI] 1·5-3·0) of age-standardised female deaths and 6·8% (5·8-8·0) of age-standardised male deaths. Among the population aged 15-49 years, alcohol use was the leading risk factor globally in 2016, with 3·8% (95% UI 3·2-4·3) of female deaths and 12·2% (10·8-13·6) of male deaths attributable to alcohol use. For the population aged 15-49 years, female attributable DALYs were 2·3% (95% UI 2·0-2·6) and male attributable DALYs were 8·9% (7·8-9·9). The three leading causes of attributable deaths in this age group were tuberculosis (1·4% [95% UI 1·0-1·7] of total deaths), road injuries (1·2% [0·7-1·9]), and self-harm (1·1% [0·6-1·5]). For populations aged 50 years and older, cancers accounted for a large proportion of total alcohol-attributable deaths in 2016, constituting 27·1% (95% UI 21·2-33·3) of total alcohol-attributable female deaths and 18·9% (15·3-22·6) of male deaths. The level of alcohol consumption that minimised harm across health outcomes was zero (95% UI 0·0-0·8) standard drinks per week.

INTERPRETATION

Alcohol use is a leading risk factor for global disease burden and causes substantial health loss. We found that the risk of all-cause mortality, and of cancers specifically, rises with increasing levels of consumption, and the level of consumption that minimises health loss is zero. These results suggest that alcohol control policies might need to be revised worldwide, refocusing on efforts to lower overall population-level consumption.

FUNDING

Bill & Melinda Gates Foundation.

C-reactive protein concentration and risk of coronary heart disease, stroke, and mortality: an individual participant meta-analysis

BACKGROUND

Associations of C-reactive protein (CRP) concentration with risk of major diseases can best be assessed by long-term prospective follow-up of large numbers of people. We assessed the associations of CRP concentration with risk of vascular and non-vascular outcomes under different circumstances.

METHODS

We meta-analysed individual records of 160 309 people without a history of vascular disease (ie, 1.31 million person-years at risk, 27 769 fatal or non-fatal disease outcomes) from 54 long-term prospective studies. Within-study regression analyses were adjusted for within-person variation in risk factor levels.

RESULTS

Log(e) CRP concentration was linearly associated with several conventional risk factors and inflammatory markers, and nearly log-linearly with the risk of ischaemic vascular disease and non-vascular mortality. Risk ratios (RRs) for coronary heart disease per 1-SD higher log(e) CRP concentration (three-fold higher) were 1.63 (95% CI 1.51-1.76) when initially adjusted for age and sex only, and 1.37 (1.27-1.48) when adjusted further for conventional risk factors; 1.44 (1.32-1.57) and 1.27 (1.15-1.40) for ischaemic stroke; 1.71 (1.53-1.91) and 1.55 (1.37-1.76) for vascular mortality; and 1.55 (1.41-1.69) and 1.54 (1.40-1.68) for non-vascular mortality. RRs were largely unchanged after exclusion of smokers or initial follow-up. After further adjustment for fibrinogen, the corresponding RRs were 1.23 (1.07-1.42) for coronary heart disease; 1.32 (1.18-1.49) for ischaemic stroke; 1.34 (1.18-1.52) for vascular mortality; and 1.34 (1.20-1.50) for non-vascular mortality.

INTERPRETATION

CRP concentration has continuous associations with the risk of coronary heart disease, ischaemic stroke, vascular mortality, and death from several cancers and lung disease that are each of broadly similar size. The relevance of CRP to such a range of disorders is unclear. Associations with ischaemic vascular disease depend considerably on conventional risk factors and other markers of inflammation.

FUNDING

British Heart Foundation, UK Medical Research Council, BUPA Foundation, and GlaxoSmithKline.

Case-control study of human papillomavirus and oropharyngeal cancer

BACKGROUND

Substantial molecular evidence suggests a role for human papillomavirus (HPV) in the pathogenesis of oropharyngeal squamous-cell carcinoma, but epidemiologic data have been inconsistent.

METHODS

We performed a hospital-based, case-control study of 100 patients with newly diagnosed oropharyngeal cancer and 200 control patients without cancer to evaluate associations between HPV infection and oropharyngeal cancer. Multivariate logistic-regression models were used for case-control comparisons.

RESULTS

A high lifetime number of vaginal-sex partners (26 or more) was associated with oropharyngeal cancer (odds ratio, 3.1; 95% confidence interval [CI], 1.5 to 6.5), as was a high lifetime number of oral-sex partners (6 or more) (odds ratio, 3.4; 95% CI, 1.3 to 8.8). The degree of association increased with the number of vaginal-sex and oral-sex partners (P values for trend, 0.002 and 0.009, respectively). Oropharyngeal cancer was significantly associated with oral HPV type 16 (HPV-16) infection (odds ratio, 14.6; 95% CI, 6.3 to 36.6), oral infection with any of 37 types of HPV (odds ratio, 12.3; 95% CI, 5.4 to 26.4), and seropositivity for the HPV-16 L1 capsid protein (odds ratio, 32.2; 95% CI, 14.6 to 71.3). HPV-16 DNA was detected in 72% (95% CI, 62 to 81) of 100 paraffin-embedded tumor specimens, and 64% of patients with cancer were seropositive for the HPV-16 oncoprotein E6, E7, or both. HPV-16 L1 seropositivity was highly associated with oropharyngeal cancer among subjects with a history of heavy tobacco and alcohol use (odds ratio, 19.4; 95% CI, 3.3 to 113.9) and among those without such a history (odds ratio, 33.6; 95% CI, 13.3 to 84.8). The association was similarly increased among subjects with oral HPV-16 infection, regardless of their tobacco and alcohol use. By contrast, tobacco and alcohol use increased the association with oropharyngeal cancer primarily among subjects without exposure to HPV-16.

CONCLUSIONS

Oral HPV infection is strongly associated with oropharyngeal cancer among subjects with or without the established risk factors of tobacco and alcohol use.

Prevalence of sleep-disordered breathing in the general population: the HypnoLaus study

BACKGROUND

Sleep-disordered breathing is associated with major morbidity and mortality. However, its prevalence has mainly been selectively studied in populations at risk for sleep-disordered breathing or cardiovascular diseases. Taking into account improvements in recording techniques and new criteria used to define respiratory events, we aimed to assess the prevalence of sleep-disordered breathing and associated clinical features in a large population-based sample.

METHODS

Between Sept 1, 2009, and June 30, 2013, we did a population-based study (HypnoLaus) in Lausanne, Switzerland. We invited a cohort of 3043 consecutive participants of the CoLaus/PsyCoLaus study to take part. Polysomnography data from 2121 people were included in the final analysis. 1024 (48%) participants were men, with a median age of 57 years (IQR 49-68, range 40-85) and mean body-mass index (BMI) of 25·6 kg/m(2) (SD 4·1). Participants underwent complete polysomnographic recordings at home and had extensive phenotyping for diabetes, hypertension, metabolic syndrome, and depression. The primary outcome was prevalence of sleep-disordered breathing, assessed by the apnoea-hypopnoea index.

FINDINGS

The median apnoea-hypopnoea index was 6·9 events per h (IQR 2·7-14·1) in women and 14·9 per h (7·2-27·1) in men. The prevalence of moderate-to-severe sleep-disordered breathing (≥15 events per h) was 23·4% (95% CI 20·9-26·0) in women and 49·7% (46·6-52·8) in men. After multivariable adjustment, the upper quartile for the apnoea-hypopnoea index (>20·6 events per h) was associated independently with the presence of hypertension (odds ratio 1·60, 95% CI 1·14-2·26; p=0·0292 for trend across severity quartiles), diabetes (2·00, 1·05-3·99; p=0·0467), metabolic syndrome (2·80, 1·86-4·29; p<0·0001), and depression (1·92, 1·01-3·64; p=0·0292).

INTERPRETATION

The high prevalence of sleep-disordered breathing recorded in our population-based sample might be attributable to the increased sensitivity of current recording techniques and scoring criteria. These results suggest that sleep-disordered breathing is highly prevalent, with important public health outcomes, and that the definition of the disorder should be revised.

FUNDING

Faculty of Biology and Medicine of Lausanne, Lausanne University Hospital, Swiss National Science Foundation, Leenaards Foundation, GlaxoSmithKline, Ligue Pulmonaire Vaudoise.

General and abdominal adiposity and risk of death in Europe

BACKGROUND

Previous studies have relied predominantly on the body-mass index (BMI, the weight in kilograms divided by the square of the height in meters) to assess the association of adiposity with the risk of death, but few have examined whether the distribution of body fat contributes to the prediction of death.

METHODS

We examined the association of BMI, waist circumference, and waist-to-hip ratio with the risk of death among 359,387 participants from nine countries in the European Prospective Investigation into Cancer and Nutrition (EPIC). We used a Cox regression analysis, with age as the time variable, and stratified the models according to study center and age at recruitment, with further adjustment for educational level, smoking status, alcohol consumption, physical activity, and height.

RESULTS

During a mean follow-up of 9.7 years, 14,723 participants died. The lowest risks of death related to BMI were observed at a BMI of 25.3 for men and 24.3 for women. After adjustment for BMI, waist circumference and waist-to-hip ratio were strongly associated with the risk of death. Relative risks among men and women in the highest quintile of waist circumference were 2.05 (95% confidence interval [CI], 1.80 to 2.33) and 1.78 (95% CI, 1.56 to 2.04), respectively, and in the highest quintile of waist-to-hip ratio, the relative risks were 1.68 (95% CI, 1.53 to 1.84) and 1.51 (95% CI, 1.37 to 1.66), respectively. BMI remained significantly associated with the risk of death in models that included waist circumference or waist-to-hip ratio (P<0.001).

CONCLUSIONS

These data suggest that both general adiposity and abdominal adiposity are associated with the risk of death and support the use of waist circumference or waist-to-hip ratio in addition to BMI in assessing the risk of death.

The Burden of Primary Liver Cancer and Underlying Etiologies From 1990 to 2015 at the Global, Regional, and National Level: Results From the Global Burden of Disease Study 2015

IMPORTANCE

Liver cancer is among the leading causes of cancer deaths globally. The most common causes for liver cancer include hepatitis B virus (HBV) and hepatitis C virus (HCV) infection and alcohol use.

OBJECTIVE

To report results of the Global Burden of Disease (GBD) 2015 study on primary liver cancer incidence, mortality, and disability-adjusted life-years (DALYs) for 195 countries or territories from 1990 to 2015, and present global, regional, and national estimates on the burden of liver cancer attributable to HBV, HCV, alcohol, and an “other” group that encompasses residual causes.

DESIGN, SETTINGS, AND PARTICIPANTS

Mortality was estimated using vital registration and cancer registry data in an ensemble modeling approach. Single-cause mortality estimates were adjusted for all-cause mortality. Incidence was derived from mortality estimates and the mortality-to-incidence ratio. Through a systematic literature review, data on the proportions of liver cancer due to HBV, HCV, alcohol, and other causes were identified. Years of life lost were calculated by multiplying each death by a standard life expectancy. Prevalence was estimated using mortality-to-incidence ratio as surrogate for survival. Total prevalence was divided into 4 sequelae that were multiplied by disability weights to derive years lived with disability (YLDs). DALYs were the sum of years of life lost and YLDs.

MAIN OUTCOMES AND MEASURES

Liver cancer mortality, incidence, YLDs, years of life lost, DALYs by etiology, age, sex, country, and year.

RESULTS

There were 854 000 incident cases of liver cancer and 810 000 deaths globally in 2015, contributing to 20 578 000 DALYs. Cases of incident liver cancer increased by 75% between 1990 and 2015, of which 47% can be explained by changing population age structures, 35% by population growth, and −8% to changing age-specific incidence rates. The male-to-female ratio for age-standardized liver cancer mortality was 2.8. Globally, HBV accounted for 265 000 liver cancer deaths (33%), alcohol for 245 000 (30%), HCV for 167 000 (21%), and other causes for 133 000 (16%) deaths, with substantial variation between countries in the underlying etiologies.

CONCLUSIONS AND RELEVANCE

Liver cancer is among the leading causes of cancer deaths in many countries. Causes of liver cancer differ widely among populations. Our results show that most cases of liver cancer can be prevented through vaccination, antiviral treatment, safe blood transfusion and injection practices, as well as interventions to reduce excessive alcohol use. In line with the Sustainable Development Goals, the identification and elimination of risk factors for liver cancer will be required to achieve a sustained reduction in liver cancer burden. The GBD study can be used to guide these prevention efforts.

Global and regional effects of potentially modifiable risk factors associated with acute stroke in 32 countries (INTERSTROKE): a case-control study

BACKGROUND

Stroke is a leading cause of death and disability, especially in low-income and middle-income countries. We sought to quantify the importance of potentially modifiable risk factors for stroke in different regions of the world, and in key populations and primary pathological subtypes of stroke.

METHODS

We completed a standardised international case-control study in 32 countries in Asia, America, Europe, Australia, the Middle East, and Africa. Cases were patients with acute first stroke (within 5 days of symptom onset and 72 h of hospital admission). Controls were hospital-based or community-based individuals with no history of stroke, and were matched with cases, recruited in a 1:1 ratio, for age and sex. All participants completed a clinical assessment and were requested to provide blood and urine samples. Odds ratios (OR) and their population attributable risks (PARs) were calculated, with 99% confidence intervals.

FINDINGS

Between Jan 11, 2007, and Aug 8, 2015, 26 919 participants were recruited from 32 countries (13 447 cases [10 388 with ischaemic stroke and 3059 intracerebral haemorrhage] and 13 472 controls). Previous history of hypertension or blood pressure of 140/90 mm Hg or higher (OR 2·98, 99% CI 2·72-3·28; PAR 47·9%, 99% CI 45·1-50·6), regular physical activity (0·60, 0·52-0·70; 35·8%, 27·7-44·7), apolipoprotein (Apo)B/ApoA1 ratio (1·84, 1·65-2·06 for highest vs lowest tertile; 26·8%, 22·2-31·9 for top two tertiles vs lowest tertile), diet (0·60, 0·53-0·67 for highest vs lowest tertile of modified Alternative Healthy Eating Index [mAHEI]; 23·2%, 18·2-28·9 for lowest two tertiles vs highest tertile of mAHEI), waist-to-hip ratio (1·44, 1·27-1·64 for highest vs lowest tertile; 18·6%, 13·3-25·3 for top two tertiles vs lowest), psychosocial factors (2·20, 1·78-2·72; 17·4%, 13·1-22·6), current smoking (1·67, 1·49-1·87; 12·4%, 10·2-14·9), cardiac causes (3·17, 2·68-3·75; 9·1%, 8·0-10·2), alcohol consumption (2·09, 1·64-2·67 for high or heavy episodic intake vs never or former drinker; 5·8%, 3·4-9·7 for current alcohol drinker vs never or former drinker), and diabetes mellitus (1·16, 1·05-1·30; 3·9%, 1·9-7·6) were associated with all stroke. Collectively, these risk factors accounted for 90·7% of the PAR for all stroke worldwide (91·5% for ischaemic stroke, 87·1% for intracerebral haemorrhage), and were consistent across regions (ranging from 82·7% in Africa to 97·4% in southeast Asia), sex (90·6% in men and in women), and age groups (92·2% in patients aged ≤55 years, 90·0% in patients aged >55 years). We observed regional variations in the importance of individual risk factors, which were related to variations in the magnitude of ORs (rather than direction, which we observed for diet) and differences in prevalence of risk factors among regions. Hypertension was more associated with intracerebral haemorrhage than with ischaemic stroke, whereas current smoking, diabetes, apolipoproteins, and cardiac causes were more associated with ischaemic stroke (p<0·0001).

INTERPRETATION

Ten potentially modifiable risk factors are collectively associated with about 90% of the PAR of stroke in each major region of the world, among ethnic groups, in men and women, and in all ages. However, we found important regional variations in the relative importance of most individual risk factors for stroke, which could contribute to worldwide variations in frequency and case-mix of stroke. Our findings support developing both global and region-specific programmes to prevent stroke.

FUNDING

Canadian Institutes of Health Research, Heart and Stroke Foundation of Canada, Canadian Stroke Network, Health Research Board Ireland, Swedish Research Council, Swedish Heart and Lung Foundation, The Health & Medical Care Committee of the Regional Executive Board, Region Västra Götaland (Sweden), AstraZeneca, Boehringer Ingelheim (Canada), Pfizer (Canada), MSD, Chest, Heart and Stroke Scotland, and The Stroke Association, with support from The UK Stroke Research Network.

21st-century hazards of smoking and benefits of cessation in the United States

BACKGROUND

Extrapolation from studies in the 1980s suggests that smoking causes 25% of deaths among women and men 35 to 69 years of age in the United States. Nationally representative measurements of the current risks of smoking and the benefits of cessation at various ages are unavailable.

METHODS

We obtained smoking and smoking-cessation histories from 113,752 women and 88,496 men 25 years of age or older who were interviewed between 1997 and 2004 in the U.S. National Health Interview Survey and related these data to the causes of deaths that occurred by December 31, 2006 (8236 deaths in women and 7479 in men). Hazard ratios for death among current smokers, as compared with those who had never smoked, were adjusted for age, educational level, adiposity, and alcohol consumption.

RESULTS

For participants who were 25 to 79 years of age, the rate of death from any cause among current smokers was about three times that among those who had never smoked (hazard ratio for women, 3.0; 99% confidence interval [CI], 2.7 to 3.3; hazard ratio for men, 2.8; 99% CI, 2.4 to 3.1). Most of the excess mortality among smokers was due to neoplastic, vascular, respiratory, and other diseases that can be caused by smoking. The probability of surviving from 25 to 79 years of age was about twice as great in those who had never smoked as in current smokers (70% vs. 38% among women and 61% vs. 26% among men). Life expectancy was shortened by more than 10 years among the current smokers, as compared with those who had never smoked. Adults who had quit smoking at 25 to 34, 35 to 44, or 45 to 54 years of age gained about 10, 9, and 6 years of life, respectively, as compared with those who continued to smoke.

CONCLUSIONS

Smokers lose at least one decade of life expectancy, as compared with those who have never smoked. Cessation before the age of 40 years reduces the risk of death associated with continued smoking by about 90%.

Age at onset of alcohol use and its association with DSM-IV alcohol abuse and dependence: results from the National Longitudinal Alcohol Epidemiologic Survey

Data from 27,616 current and former drinkers interviewed in the 1992 National Longitudinal Alcohol Epidemiologic Survey were used to examine the relationship between age at first use of alcohol and the prevalence of lifetime alcohol abuse and alcohol dependence, among all U.S. adults 18 years of age and over and within subgroups defined by sex and race. The rates of lifetime dependence declined from more than 40% among individuals who started drinking at ages 14 or younger to roughly 10% among those who started drinking at ages 20 and older. The rates of lifetime abuse declined from just over 11% among those who initiated use of alcohol at ages 16 or younger to approximately 4% among those whose onset of use was at ages 20 or older. After using multivariate logistic regression models to adjust for potential confounders, the odds of dependence decreased by 14% with each increasing year of age at onset of use, and the odds of abuse decreased by 8%. These findings are discussed with respect to their implications for prevention policies and the need to integrate epidemiological and intervention research.

The prevalence and etiology of elevated aminotransferase levels in the United States

Chronic liver disease is a major cause of morbidity and mortality in the United States. Although often used to detect liver disease, the prevalence and etiology of elevated aminotransferases are unknown. We analyzed data on adults ages 17 yr and older (N = 15,676) from the Third National Health and Nutrition Examination Survey (1988-1994). Participants were classified as having elevated aminotransferase levels if either aspartate aminotransferase or alanine aminotransferase was elevated above normal. Aminotransferase elevation was classified as "explained" if there was laboratory evidence of hepatitis B or C infection, iron overload, or if there was a history of alcohol consumption. Analyses were weighted to provide national estimates. The prevalence of aminotransferase elevation in the United States was 7.9%. Aminotransferase elevation was more common in men compared to women (9.3% vs 6.6%, p = 0.002), in Mexican Americans (14.9%) and non-Hispanic blacks (8.1%) compared to non-Hispanic whites (7.1%, p < 0.001). High alcohol consumption, hepatitis B or C infection and high transferrin saturation were found in only 31.0% of cases. Aminotransferase elevation was unexplained in the majority (69.0%). In both men and women, unexplained aminotransferase elevation was significantly associated with higher body mass index, waist circumference, triglycerides, fasting insulin, and lower HDL; and with type 2 diabetes and hypertension in women (all p < 0.05). Aminotransferase elevation was common in the United States, and the majority could not be unexplained by alcohol consumption, viral hepatitis or hemochromatosis. Unexplained aminotransferase elevation was strongly associated with adiposity and other features of the metabolic syndrome, and thus may represent nonalcoholic fatty liver disease.

The Alcohol Use Disorder and Associated Disabilities Interview Schedule-IV (AUDADIS-IV): reliability of alcohol consumption, tobacco use, family history of depression and psychiatric diagnostic modules in a general population sample

BACKGROUND

the purpose of this study was to assess the test-retest reliability of newly introduced or revised modules of the Alcohol Use Disorder and Associated Disabilities Interview Schedule-IV (AUDADIS-IV), including alcohol consumption, tobacco use, family history of depression, and selected DSM-IV axis I and II psychiatric disorders.

METHODS

kappa and intraclass correlation coefficients were calculated for the AUDADIS-IV modules using a test-retest design among a total of 2657 respondents, in subsets of approximately 400, randomly drawn from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC).

RESULTS

reliabilities for alcohol consumption, tobacco use and family history of major depression measures were good to excellent, while reliabilities for selected DSM-IV axis I and II disorders were fair to good. The reliabilities of dimensional symptom scales of DSM-IV axis I and axis II disorders exceeded those of their dichotomous diagnostic counterparts and were generally in the good to excellent range.

CONCLUSIONS

the high reliability of alcohol consumption, tobacco use, family history of depression and psychiatric disorder modules found in this study suggests that the AUDADIS-IV can be a useful tool in various research settings, particularly in studies of the general population, the target population for which it was designed.

Alcohol consumption and site-specific cancer risk: a comprehensive dose-response meta-analysis

BACKGROUND

Alcohol is a risk factor for cancer of the oral cavity, pharynx, oesophagus, colorectum, liver, larynx and female breast, whereas its impact on other cancers remains controversial.

METHODS

We investigated the effect of alcohol on 23 cancer types through a meta-analytic approach. We used dose-response meta-regression models and investigated potential sources of heterogeneity.

RESULTS

A total of 572 studies, including 486 538 cancer cases, were identified. Relative risks (RRs) for heavy drinkers compared with nondrinkers and occasional drinkers were 5.13 for oral and pharyngeal cancer, 4.95 for oesophageal squamous cell carcinoma, 1.44 for colorectal, 2.65 for laryngeal and 1.61 for breast cancer; for those neoplasms there was a clear dose-risk relationship. Heavy drinkers also had a significantly higher risk of cancer of the stomach (RR 1.21), liver (2.07), gallbladder (2.64), pancreas (1.19) and lung (1.15). There was indication of a positive association between alcohol consumption and risk of melanoma and prostate cancer. Alcohol consumption and risk of Hodgkin's and Non-Hodgkin's lymphomas were inversely associated.

CONCLUSIONS

Alcohol increases risk of cancer of oral cavity and pharynx, oesophagus, colorectum, liver, larynx and female breast. There is accumulating evidence that alcohol drinking is associated with some other cancers such as pancreas and prostate cancer and melanoma.

Sperm morphology, motility, and concentration in fertile and infertile men

BACKGROUND

Although semen analysis is routinely used to evaluate the male partner in infertile couples, sperm measurements that discriminate between fertile and infertile men are not well defined.

METHODS

We evaluated two semen specimens from each of the male partners in 765 infertile couples and 696 fertile couples at nine sites. The female partners in the infertile couples had normal results on fertility evaluation. The sperm concentration and motility were determined at the sites; semen smears were stained at the sites and shipped to a central laboratory for an assessment of morphologic features of sperm with the use of strict criteria. We used classification-and-regression-tree analysis to estimate threshold values for subfertility and fertility with respect to the sperm concentration, motility, and morphology. We also used an analysis of receiver-operating-characteristic curves to assess the relative value of these sperm measurements in discriminating between fertile and infertile men.

RESULTS

The subfertile ranges were a sperm concentration of less than 13.5 x 10(6) per milliliter, less than 32 percent of sperm with motility, and less than 9 percent with normal morphologic features. The fertile ranges were a concentration of more than 48.0 x 10(6) per milliliter, greater than 63 percent motility, and greater than 12 percent normal morphologic features. Values between these ranges indicated indeterminate fertility. There was extensive overlap between the fertile and the infertile men within both the subfertile and the fertile ranges for all three measurements. Although each of the sperm measurements helped to distinguish between fertile and infertile men, none was a powerful discriminator. The percentage of sperm with normal morphologic features had the greatest discriminatory power.

CONCLUSIONS

Threshold values for sperm concentration, motility, and morphology can be used to classify men as subfertile, of indeterminate fertility, or fertile. None of the measures, however, are diagnostic of infertility.

Interaction between tobacco and alcohol use and the risk of head and neck cancer: pooled analysis in the International Head and Neck Cancer Epidemiology Consortium

BACKGROUND

The magnitude of risk conferred by the interaction between tobacco and alcohol use on the risk of head and neck cancers is not clear because studies have used various methods to quantify the excess head and neck cancer burden.

METHODS

We analyzed individual-level pooled data from 17 European and American case-control studies (11,221 cases and 16,168 controls) participating in the International Head and Neck Cancer Epidemiology consortium. We estimated the multiplicative interaction parameter (psi) and population attributable risks (PAR).

RESULTS

A greater than multiplicative joint effect between ever tobacco and alcohol use was observed for head and neck cancer risk (psi = 2.15; 95% confidence interval, 1.53-3.04). The PAR for tobacco or alcohol was 72% (95% confidence interval, 61-79%) for head and neck cancer, of which 4% was due to alcohol alone, 33% was due to tobacco alone, and 35% was due to tobacco and alcohol combined. The total PAR differed by subsite (64% for oral cavity cancer, 72% for pharyngeal cancer, 89% for laryngeal cancer), by sex (74% for men, 57% for women), by age (33% for cases <45 years, 73% for cases >60 years), and by region (84% in Europe, 51% in North America, 83% in Latin America).

CONCLUSIONS

Our results confirm that the joint effect between tobacco and alcohol use is greater than multiplicative on head and neck cancer risk. However, a substantial proportion of head and neck cancers cannot be attributed to tobacco or alcohol use, particularly for oral cavity cancer and for head and neck cancer among women and among young-onset cases.

Alcohol consumption and mortality among middle-aged and elderly U.S. adults

BACKGROUND

Alcohol consumption has both adverse and beneficial effects on survival. We examined the balance of these in a large prospective study of mortality among U.S. adults.

METHODS

Of 490,000 men and women (mean age, 56 years; range, 30 to 104) who reported their alcohol and tobacco use in 1982, 46,000 died during nine years of follow-up. We compared cause-specific and rates of death from all causes across categories of base-line alcohol consumption, adjusting for other risk factors, and related drinking and smoking habits to the cumulative probability of dying between the ages of 35 and 69 years.

RESULTS

Causes of death associated with drinking were cirrhosis and alcoholism; cancers of the mouth, esophagus, pharynx, larynx, and liver combined; breast cancer in women; and injuries and other external causes in men. The mortality from breast cancer was 30 percent higher among women reporting at least one drink daily than among nondrinkers (relative risk, 1.3; 95 percent confidence interval, 1.1 to 1.6). The rates of death from all cardiovascular diseases were 30 to 40 percent lower among men (relative risk, 0.7; 95 percent confidence interval, 0.7 to 0.8) and women (relative risk, 0.6; 95 percent confidence interval, 0.6 to 0.7) reporting at least one drink daily than among nondrinkers, with little relation to the level of consumption. The overall death rates were lowest among men and women reporting about one drink daily. Mortality from all causes increased with heavier drinking, particularly among adults under age 60 with lower risk of cardiovascular disease. Alcohol consumption was associated with a small reduction in the overall risk of death in middle age (ages 35 to 69), whereas smoking approximately doubled this risk.

CONCLUSIONS

In this middle-aged and elderly population, moderate alcohol consumption slightly reduced overall mortality. The benefit depended in part on age and background cardiovascular risk and was far smaller than the large increase in risk produced by tobacco.

Age at first alcohol use: a risk factor for the development of alcohol disorders

OBJECTIVE

This study aimed to describe the natural course of DSM-III-R alcohol disorders as a function of age at first alcohol use and to investigate the influence of early use as a risk factor for progression to the development of alcohol disorders, exclusive of the effect of confounding influences.

METHOD

Data were obtained from a community sample (N=5,856) of lifetime drinkers participating in the 1990-1991 Mental Health Supplement of the Ontario Health Survey.

RESULTS

Survival analyses revealed a rapid progression to alcohol-related harm among those who reported having their first drink at ages 11-14. After 10 years, 13.5% of the subjects who began to drink at ages 11 and 12 met the criteria for a diagnosis of alcohol abuse, and 15.9% had a diagnosis of dependence. Rates for subjects who began to drink at ages 13 and 14 were 13.7% and 9.0%, respectively. In contrast, rates for those who started drinking at ages 19 and older were 2.0% and 1.0%. Unexpectedly, a delay in progression to harm was observed for the youngest drinkers (ages 10 and under). Hazard regression analyses revealed a nonlinear effect of age at first alcohol use, marked by an elevated risk of developing disorders among subjects first using alcohol at ages 11-14.

CONCLUSIONS

First use of alcohol at ages 11-14 greatly heightens the risk of progression to the development of alcohol disorders and therefore is a reasonable target for intervention strategies that seek to delay first use as a means of averting problems later in life.

NCD Countdown 2030: worldwide trends in non-communicable disease mortality and progress towards Sustainable Development Goal target 3.4

The third UN High-Level Meeting on Non-Communicable Diseases (NCDs) on Sept 27, 2018, will review national and global progress towards the prevention and control of NCDs, and provide an opportunity to renew, reinforce, and enhance commitments to reduce their burden. NCD Countdown 2030 is an independent collaboration to inform policies that aim to reduce the worldwide burden of NCDs, and to ensure accountability towards this aim. In 2016, an estimated 40·5 million (71%) of the 56·9 million worldwide deaths were from NCDs. Of these, an estimated 1·7 million (4% of NCD deaths) occurred in people younger than 30 years of age, 15·2 million (38%) in people aged between 30 years and 70 years, and 23·6 million (58%) in people aged 70 years and older. An estimated 32·2 million NCD deaths (80%) were due to cancers, cardiovascular diseases, chronic respiratory diseases, and diabetes, and another 8·3 million (20%) were from other NCDs. Women in 164 (88%) and men in 165 (89%) of 186 countries and territories had a higher probability of dying before 70 years of age from an NCD than from communicable, maternal, perinatal, and nutritional conditions combined. Globally, the lowest risks of NCD mortality in 2016 were seen in high-income countries in Asia-Pacific, western Europe, and Australasia, and in Canada. The highest risks of dying from NCDs were observed in low-income and middle-income countries, especially in sub-Saharan Africa, and, for men, in central Asia and eastern Europe. Sustainable Development Goal (SDG) target 3.4-a one-third reduction, relative to 2015 levels, in the probability of dying between 30 years and 70 years of age from cancers, cardiovascular diseases, chronic respiratory diseases, and diabetes by 2030-will be achieved in 35 countries (19%) for women, and 30 (16%) for men, if these countries maintain or surpass their 2010-2016 rate of decline in NCD mortality. Most of these are high-income countries with already-low NCD mortality, and countries in central and eastern Europe. An additional 50 (27%) countries for women and 35 (19%) for men are projected to achieve such a reduction in the subsequent decade, and thus, with slight acceleration of decline, could meet the 2030 target. 86 (46%) countries for women and 97 (52%) for men need implementation of policies that substantially increase the rates of decline. Mortality from the four NCDs included in SDG target 3.4 has stagnated or increased since 2010 among women in 15 (8%) countries and men in 24 (13%) countries. NCDs and age groups other than those included in the SDG target 3.4 are responsible for a higher risk of death in low-income and middle-income countries than in high-income countries. Substantial reduction of NCD mortality requires policies that considerably reduce tobacco and alcohol use and blood pressure, and equitable access to efficacious and high-quality preventive and curative care for acute and chronic NCDs.

Incidence of and risk factors for falls and injurious falls among the community-dwelling elderly

To determine the frequency of and risk factors for falls and injurious falls in the noninstitutionalized elderly, the authors conducted a follow-up study of 409 community-dwelling persons aged 65 years or more in west-central Montreal, Quebec, Canada, from May 1987 to October 1988. Following an initial at-home interview, each subject was telephoned every 4 weeks for 48 weeks for collection of data on falls experienced since the last contact. Each of the 12 follow-up interviews was completed by at least 90% of the subjects eligible for interview. Data were also collected in the follow-up interviews on time-varying exposures. Twenty-nine percent of the subjects fell during follow-up; 17.6% fell once, and 11.5% fell two or more times. The incidence rate for falls was 41.4 falls per 1,000 person-months. The majority of falls resulted in no injury or in minor injury only. Potential risk factors investigated included sociodemographic variables, physical activity, alcohol consumption, acute and chronic health problems, dizziness, mobility, and medications. Multivariate analyses showed that the following factors were statistically significantly associated with an increased rate of falls: dizziness (incidence rate ratio (IRR) = 2.0), frequent physical activity (IRR = 2.0), having days on which activities were limited because of a health problem (IRR = 1.8), having trouble walking 400 m (IRR = 1.6), and having trouble bending down (IRR = 1.4). Factors which were protective included diversity of physical activities (IRR = 0.6), daily alcohol consumption (IRR = 0.5), having days spent in bed because of a health problem (IRR = 0.5), and taking heart medication (IRR = 0.6). Risk factors for injurious falls were similar.

Alcohol and public health

Alcoholic beverages, and the problems they engender, have been familiar fixtures in human societies since the beginning of recorded history. We review advances in alcohol science in terms of three topics: the epidemiology of alcohol's role in health and illness; the treatment of alcohol use disorders in a public health perspective; and policy research and options. Research has contributed substantially to our understanding of the relation of drinking to specific disorders, and has shown that the relation between alcohol consumption and health outcomes is complex and multidimensional. Alcohol is causally related to more than 60 different medical conditions. Overall, 4% of the global burden of disease is attributable to alcohol, which accounts for about as much death and disability globally as tobacco and hypertension. Treatment research shows that early intervention in primary care is feasible and effective, and a variety of behavioural and pharmacological interventions are available to treat alcohol dependence. This evidence suggests that treatment of alcohol-related problems should be incorporated into a public health response to alcohol problems. Additionally, evidence-based preventive measures are available at both the individual and population levels, with alcohol taxes, restrictions on alcohol availability, and drinking-driving countermeasures among the most effective policy options. Despite the scientific advances, alcohol problems continue to present a major challenge to medicine and public health, in part because population-based public health approaches have been neglected in favour of approaches oriented to the individual that tend to be more palliative than preventative.

Epidemiology of alcohol and other drug use among American college students

OBJECTIVE

This article provides information on the extent of alcohol use and other drug use among American college students.

METHOD

Five different sources of data are examined for estimating recent levels of alcohol (and other drug) use among college students: Harvard School of Public Health College Alcohol Study (CAS), the Core Institute (CORE), Monitoring the Future (MTF), National College Health Risk Behavior Survey (NCHRBS) and National Household Survey on Drug Abuse (NHSDA).

RESULTS

Alcohol use rates are very high among college students. Approximately two of five American college students were heavy drinkers, defined as having had five or more drinks in a row in the past 2 weeks. Alcohol use is higher among male than female students. White students are highest in heavy drinking, black students are lowest and Hispanic students are intermediate. Use of alcohol--but not cigarettes, marijuana and cocaine--is higher among college students than among noncollege age-mates. Longitudinal data show that, while in high school, students who go on to attend college have lower rates of heavy drinking than do those who will not attend college. Both groups increase their heavy drinking after high school graduation, but the college students increase distinctly more and actually surpass their nonstudent age-mates. Trend data from 1980 to 1999 show some slight improvement in recent years.

CONCLUSIONS

Despite improvements in the past 20 years, colleges need to do more to reduce heavy alcohol use among students.

Descriptive and injunctive norms in college drinking: a meta-analytic integration

OBJECTIVE

Many college students overestimate both the drinking behaviors (descriptive norms) and the approval of drinking (injunctive norms) of their peers. As a result, consistent self-other discrepancies (SODs) have been observed, in which self-perceptions of drinking behaviors and approval of drinking usually are lower than comparable judgments of others. These SODs form the foundation of the currently popular "social norms approach" to alcohol abuse prevention, which conveys to students the actual campus norms regarding drinking behaviors and approval of alcohol use. However, little attention has been paid to the factors that can influence the magnitude of SODs. This research was conducted to address these issues.

METHOD

This meta-analytic integration of 23 studies evaluated the influence of five predictors of SODs: norm type (injunctive or descriptive), gender, reference group, question specificity and campus size. These studies rendered 102 separate tests of SODs in descriptive and injunctive forms, representing the responses of 53,825 participants.

RESULTS

All five predictors were significantly related to self-other differences in the perception of norms. Greater SODs were evident for injunctive norms, estimates by women, distal reference groups and nonspecific questions, as well as on smaller campuses.

CONCLUSIONS

More systematic attention should be given to how norms are assessed. In particular, SODs can be maximized or minimized, depending on the specificity of the behaviors/attitudes evaluated and the reference groups chosen for comparison.

Global statistics on alcohol, tobacco and illicit drug use: 2017 status report

AIMS

This review provides an up-to-date curated source of information on alcohol, tobacco and illicit drug use and their associated mortality and burden of disease. Limitations in the data are also discussed, including how these can be addressed in the future.

METHODS

Online data sources were identified through expert review. Data were obtained mainly from the World Health Organization, United Nations Office on Drugs and Crime and Institute for Health Metrics and Evaluation.

RESULTS

In 2015, the estimated prevalence among the adult population was 18.4% for heavy episodic alcohol use (in the past 30 days); 15.2% for daily tobacco smoking; and 3.8, 0.77, 0.37 and 0.35% for past-year cannabis, amphetamine, opioid and cocaine use, respectively. European regions had the highest prevalence of heavy episodic alcohol use and daily tobacco use. The age-standardized prevalence of alcohol dependence was 843.2 per 100 000 people; for cannabis, opioids, amphetamines and cocaine dependence it was 259.3, 220.4, 86.0 and 52.5 per 100 000 people, respectively. High-income North America region had among the highest rates of cannabis, opioid and cocaine dependence. Attributable disability-adjusted life-years (DALYs) were highest for tobacco smoking (170.9 million DALYs), followed by alcohol (85.0 million) and illicit drugs (27.8 million). Substance-attributable mortality rates were highest for tobacco smoking (110.7 deaths per 100 000 people), followed by alcohol and illicit drugs (33.0 and 6.9 deaths per 100 000 people, respectively). Attributable age-standardized mortality rates and DALYs for alcohol and illicit drugs were highest in eastern Europe; attributable age-standardized tobacco mortality rates and DALYs were highest in Oceania.

CONCLUSIONS

In 2015 alcohol use and tobacco smoking use between them cost the human population more than a quarter of a billion disability-adjusted life years, with illicit drugs costing further tens of millions. Europeans suffered proportionately more, but in absolute terms the mortality rate was greatest in low- and middle-income countries with large populations and where the quality of data was more limited. Better standardized and rigorous methods for data collection, collation and reporting are needed to assess more accurately the geographical and temporal trends in substance use and its disease burden.