Leanne Riley

National, regional, and global trends in fasting plasma glucose and diabetes prevalence since 1980: systematic analysis of health examination surveys and epidemiological studies with 370 country-years and 2·7 million participants

BACKGROUND Data for trends in glycaemia and diabetes prevalence are needed to understand the effects of diet and lifestyle within populations, assess the performance of interventions, and plan health services. No consistent and comparable global analysis of trends has been done. We estimated trends and their uncertainties in mean fasting plasma glucose (FPG) and diabetes prevalence for adults aged 25 years and older in 199 countries and territories. METHODS We obtained data from health examination surveys and epidemiological studies (370 country-years and 2·7 million participants). We converted systematically between different glycaemic metrics. For each sex, we used a Bayesian hierarchical model to estimate mean FPG and its uncertainty by age, country, and year, accounting for whether a study was nationally, subnationally, or community representative. FINDINGS In 2008, global age-standardised mean FPG was 5·50 mmol/L (95% uncertainty interval 5·37-5·63) for men and 5·42 mmol/L (5·29-5·54) for women, having risen by 0·07 mmol/L and 0·09 mmol/L per decade, respectively. Age-standardised adult diabetes prevalence was 9·8% (8·6-11·2) in men and 9·2% (8·0-10·5) in women in 2008, up from 8·3% (6·5-10·4) and 7·5% (5·8-9·6) in 1980. The number of people with diabetes increased from 153 (127-182) million in 1980, to 347 (314-382) million in 2008. We recorded almost no change in mean FPG in east and southeast Asia and central and eastern Europe. Oceania had the largest rise, and the highest mean FPG (6·09 mmol/L, 5·73-6·49 for men; 6·08 mmol/L, 5·72-6·46 for women) and diabetes prevalence (15·5%, 11·6-20·1 for men; and 15·9%, 12·1-20·5 for women) in 2008. Mean FPG and diabetes prevalence in 2008 were also high in south Asia, Latin America and the Caribbean, and central Asia, north Africa, and the Middle East. Mean FPG in 2008 was lowest in sub-Saharan Africa, east and southeast Asia, and high-income Asia-Pacific. In high-income subregions, western Europe had the smallest rise, 0·07 mmol/L per decade for men and 0·03 mmol/L per decade for women; North America had the largest rise, 0·18 mmol/L per decade for men and 0·14 mmol/L per decade for women. INTERPRETATION Glycaemia and diabetes are rising globally, driven both by population growth and ageing and by increasing age-specific prevalences. Effective preventive interventions are needed, and health systems should prepare to detect and manage diabetes and its sequelae. FUNDING Bill & Melinda Gates Foundation and WHO.

National, regional, and global trends in body-mass index since 1980: systematic analysis of health examination surveys and epidemiological studies with 960 country-years and 9·1 million participants.

BACKGROUND Excess bodyweight is a major public health concern. However, few worldwide comparative analyses of long-term trends of body-mass index (BMI) have been done, and none have used recent national health examination surveys. We estimated worldwide trends in population mean BMI. METHODS We estimated trends and their uncertainties of mean BMI for adults 20 years and older in 199 countries and territories. We obtained data from published and unpublished health examination surveys and epidemiological studies (960 country-years and 9·1 million participants). For each sex, we used a Bayesian hierarchical model to estimate mean BMI by age, country, and year, accounting for whether a study was nationally representative. FINDINGS Between 1980 and 2008, mean BMI worldwide increased by 0·4 kg/m(2) per decade (95% uncertainty interval 0·2-0·6, posterior probability of being a true increase >0·999) for men and 0·5 kg/m(2) per decade (0·3-0·7, posterior probability >0·999) for women. National BMI change for women ranged from non-significant decreases in 19 countries to increases of more than 2·0 kg/m(2) per decade (posterior probabilities >0·99) in nine countries in Oceania. Male BMI increased in all but eight countries, by more than 2 kg/m(2) per decade in Nauru and Cook Islands (posterior probabilities >0·999). Male and female BMIs in 2008 were highest in some Oceania countries, reaching 33·9 kg/m(2) (32·8-35·0) for men and 35·0 kg/m(2) (33·6-36·3) for women in Nauru. Female BMI was lowest in Bangladesh (20·5 kg/m(2), 19·8-21·3) and male BMI in Democratic Republic of the Congo 19·9 kg/m(2) (18·2-21·5), with BMI less than 21·5 kg/m(2) for both sexes in a few countries in sub-Saharan Africa, and east, south, and southeast Asia. The USA had the highest BMI of high-income countries. In 2008, an estimated 1·46 billion adults (1·41-1·51 billion) worldwide had BMI of 25 kg/m(2) or greater, of these 205 million men (193-217 million) and 297 million women (280-315 million) were obese. INTERPRETATION Globally, mean BMI has increased since 1980. The trends since 1980, and mean population BMI in 2008, varied substantially between nations. Interventions and policies that can curb or reverse the increase, and mitigate the health effects of high BMI by targeting its metabolic mediators, are needed in most countries. FUNDING Bill & Melinda Gates Foundation and WHO.

National, regional, and global trends in systolic blood pressure since 1980: systematic analysis of health examination surveys and epidemiological studies with 786 country-years and 5·4 million participants

BACKGROUND Data for trends in blood pressure are needed to understand the effects of its dietary, lifestyle, and pharmacological determinants; set intervention priorities; and evaluate national programmes. However, few worldwide analyses of trends in blood pressure have been done. We estimated worldwide trends in population mean systolic blood pressure (SBP). METHODS We estimated trends and their uncertainties in mean SBP for adults 25 years and older in 199 countries and territories. We obtained data from published and unpublished health examination surveys and epidemiological studies (786 country-years and 5·4 million participants). For each sex, we used a Bayesian hierarchical model to estimate mean SBP by age, country, and year, accounting for whether a study was nationally representative. FINDINGS In 2008, age-standardised mean SBP worldwide was 128·1 mm Hg (95% uncertainty interval 126·7-129·4) in men and 124·4 mm Hg (123·0-125·9) in women. Globally, between 1980 and 2008, SBP decreased by 0·8 mm Hg per decade (-0·4 to 2·2, posterior probability of being a true decline=0·90) in men and 1·0 mm Hg per decade (-0·3 to 2·3, posterior probability=0·93) in women. Female SBP decreased by 3·5 mm Hg or more per decade in western Europe and Australasia (posterior probabilities ≥0·999). Male SBP fell most in high-income North America, by 2·8 mm Hg per decade (1·3-4·5, posterior probability >0·999), followed by Australasia and western Europe where it decreased by more than 2·0 mm Hg per decade (posterior probabilities >0·98). SBP rose in Oceania, east Africa, and south and southeast Asia for both sexes, and in west Africa for women, with the increases ranging 0·8-1·6 mm Hg per decade in men (posterior probabilities 0·72-0·91) and 1·0-2·7 mm Hg per decade for women (posterior probabilities 0·75-0·98). Female SBP was highest in some east and west African countries, with means of 135 mm Hg or greater. Male SBP was highest in Baltic and east and west African countries, where mean SBP reached 138 mm Hg or more. Men and women in western Europe had the highest SBP in high-income regions. INTERPRETATION On average, global population SBP decreased slightly since 1980, but trends varied significantly across regions and countries. SBP is currently highest in low-income and middle-income countries. Effective population-based and personal interventions should be targeted towards low-income and middle-income countries. FUNDING Funding Bill & Melinda Gates Foundation and WHO.

Tobacco use by youth: a surveillance report from the Global Youth Tobacco Survey project

The Global Youth Tobacco Survey (GYTS) project was developed by the World Health Organization and the US Centers for Disease Control and Prevention to track tobacco use among youth in countries across the world, using a common methodology and core questionnaire. The GYTS is school based and employs a two-stage sample design to produce representative data on smoking among students aged 13-15 years. The first stage consists of a probabilistic selection of schools, and the second consists of a random selection of classes from the participating schools. All students in the selected classes are eligible for the survey. In 1999, the GYTS was conducted in 13 countries and is currently in progress in over 30 countries. This report describes data from 12 countries: Barbados, China, Costa Rica, Fiji, Jordan, Poland, the Russian Federation (Moscow), South Africa, Sri Lanka, Ukraine (Kiev), Venezuela, and Zimbabwe. The findings show that tobacco use in the surveyed age group ranged from a high of 33% to a low of 10%. While the majority of current smokers wanted to stop smoking, very few were able to attend a cessation programme. In most countries the majority of young people reported seeing advertisements for cigarettes in media outlets, but anti-tobacco advertising was rare. The majority of young people reported being taught in school about the dangers of smoking. Environmental tobacco smoke exposure was very high in all countries. These results show that the GYTS surveillance system is enhancing the capacity of countries to design, implement, and evaluate tobacco prevention and control programmes.

National, regional, and global trends in adult overweight and obesity prevalences

BackgroundOverweight and obesity prevalence are commonly used for public and policy communication of the extent of the obesity epidemic, yet comparable estimates of trends in overweight and obesity prevalence by country are not available.MethodsWe estimated trends between 1980 and 2008 in overweight and obesity prevalence and their uncertainty for adults 20 years of age and older in 199 countries and territories. Data were from a previous study, which used a Bayesian hierarchical model to estimate mean body mass index (BMI) based on published and unpublished health examination surveys and epidemiologic studies. Here, we used the estimated mean BMIs in a regression model to predict overweight and obesity prevalence by age, country, year, and sex. The uncertainty of the estimates included both those of the Bayesian hierarchical model and the uncertainty due to cross-walking from mean BMI to overweight and obesity prevalence.ResultsThe global age-standardized prevalence of obesity nearly doubled from 6.4% (95% uncertainty interval 5.7-7.2%) in 1980 to 12.0% (11.5-12.5%) in 2008. Half of this rise occurred in the 20 years between 1980 and 2000, and half occurred in the 8 years between 2000 and 2008. The age-standardized prevalence of overweight increased from 24.6% (22.7-26.7%) to 34.4% (33.2-35.5%) during the same 28-year period. In 2008, female obesity prevalence ranged from 1.4% (0.7-2.2%) in Bangladesh and 1.5% (0.9-2.4%) in Madagascar to 70.4% (61.9-78.9%) in Tonga and 74.8% (66.7-82.1%) in Nauru. Male obesity was below 1% in Bangladesh, Democratic Republic of the Congo, and Ethiopia, and was highest in Cook Islands (60.1%, 52.6-67.6%) and Nauru (67.9%, 60.5-75.0%).ConclusionsGlobally, the prevalence of overweight and obesity has increased since 1980, and the increase has accelerated. Although obesity increased in most countries, levels and trends varied substantially. These data on trends in overweight and obesity may be used to set targets for obesity prevalence as requested at the United Nations high-level meeting on Prevention and Control of NCDs.

Monitoring and surveillance of chronic non-communicable diseases: progress and capacity in high-burden countries

The burden of chronic, non-communicable diseases in low-income and middle-income countries is increasing. We outline a framework for monitoring of such diseases and review the mortality burden and the capacity of countries to respond to them. We show data from WHO data sources and published work for prevalence of tobacco use, overweight, and cause-specific mortality in 23 low-income and middle-income countries with a high burden of non-communicable disease. Data for national capacity for chronic disease prevention and control were generated from a global assessment that was done in WHO member states in 2009-10. Although reliable data for cause-specific mortality are scarce, non-communicable diseases were estimated to be responsible for 23·4 million (or 64% of the total) deaths in the 23 countries that we analysed, with 47% occurring in people who were younger than 70 years. Tobacco use and overweight are common in most of the countries and populations we examined, but coverage of cost-effective interventions to reduce these risk factors is low. Capacity for prevention and control of non-communicable diseases, including monitoring and surveillance operations nationally, is inadequate. A surveillance framework, including a minimum set of indicators covering exposures and outcomes, is essential for policy development and assessment and for monitoring of trends in disease. Technical, human, and fiscal resource constraints are major impediments to the establishment of effective prevention and control programmes. Despite increasing awareness and commitment to address chronic disease, concrete actions by global partners to plan and implement cost-effective interventions are inadequate.

National, regional, and global trends in serum total cholesterol since 1980: systematic analysis of health examination surveys and epidemiological studies with 321 country-years and 3·0 million participants

BACKGROUND Data for trends in serum cholesterol are needed to understand the effects of its dietary, lifestyle, and pharmacological determinants; set intervention priorities; and evaluate national programmes. Previous analyses of trends in serum cholesterol were limited to a few countries, with no consistent and comparable global analysis. We estimated worldwide trends in population mean serum total cholesterol. METHODS We estimated trends and their uncertainties in mean serum total cholesterol for adults 25 years and older in 199 countries and territories. We obtained data from published and unpublished health examination surveys and epidemiological studies (321 country-years and 3·0 million participants). For each sex, we used a Bayesian hierarchical model to estimate mean total cholesterol by age, country, and year, accounting for whether a study was nationally representative. FINDINGS In 2008, age-standardised mean total cholesterol worldwide was 4·64 mmol/L (95% uncertainty interval 4·51-4·76) for men and 4·76 mmol/L (4·62-4·91) for women. Globally, mean total cholesterol changed little between 1980 and 2008, falling by less than 0·1 mmol/L per decade in men and women. Total cholesterol fell in the high-income region consisting of Australasia, North America, and western Europe, and in central and eastern Europe; the regional declines were about 0·2 mmol/L per decade for both sexes, with posterior probabilities of these being true declines 0·99 or greater. Mean total cholesterol increased in east and southeast Asia and Pacific by 0·08 mmol/L per decade (-0·06 to 0·22, posterior probability=0·86) in men and 0·09 mmol/L per decade (-0·07 to 0·26, posterior probability=0·86) in women. Despite converging trends, serum total cholesterol in 2008 was highest in the high-income region consisting of Australasia, North America, and western Europe; the regional mean was 5·24 mmol/L (5·08-5·39) for men and 5·23 mmol/L (5·03-5·43) for women. It was lowest in sub-Saharan Africa at 4·08 mmol/L (3·82-4·34) for men and 4·27 mmol/L (3·99-4·56) for women. INTERPRETATION Nutritional policies and pharmacological interventions should be used to accelerate improvements in total cholesterol in regions with decline and to curb or prevent the rise in Asian populations and elsewhere. Population-based surveillance of cholesterol needs to be improved in low-income and middle-income countries. FUNDING Bill & Melinda Gates Foundation and WHO.

Health of the world's adolescents: a synthesis of internationally comparable data

Adolescence and young adulthood offer opportunities for health gains both through prevention and early clinical intervention. Yet development of health information systems to support this work has been weak and so far lagged behind those for early childhood and adulthood. With falls in the number of deaths in earlier childhood in many countries and a shifting emphasis to non-communicable disease risks, injuries, and mental health, there are good reasons to assess the present sources of health information for young people. We derive indicators from the conceptual framework for the Series on adolescent health and assess the available data to describe them. We selected indicators for their public health importance and their coverage of major health outcomes in young people, health risk behaviours and states, risk and protective factors, social role transitions relevant to health, and health service inputs. We then specify definitions that maximise international comparability. Even with this optimisation of data usage, only seven of the 25 indicators, covered at least 50% of the worlds adolescents. The worst adolescent health profiles are in sub-Saharan Africa, with persisting high mortality from maternal and infectious causes. Risks for non-communicable diseases are spreading rapidly, with the highest rates of tobacco use and overweight, and lowest rates of physical activity, predominantly in adolescents living in low-income and middle-income countries. Even for present global health agendas, such as HIV infection and maternal mortality, data sources are incomplete for adolescents. We propose a series of steps that include better coordination and use of data collected across countries, greater harmonisation of school-based surveys, further development of strategies for socially marginalised youth, targeted research into the validity and use of these health indicators, advocating for adolescent-health information within new global health initiatives, and a recommendation that every country produce a regular report on the health of its adolescents.

A century of trends in adult human height

Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95% credible interval 17.5–22.7) and 16.5 cm (13.3–19.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8–144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries. DOI: http://dx.doi.org/10.7554/eLife.13410.001

Contribution of six risk factors to achieving the 25×25 non-communicable disease mortality reduction target: a modelling study

BACKGROUND Countries have agreed to reduce premature mortality (defined as the probability of dying between the ages of 30 years and 70 years) from four main non-communicable diseases (NCDs)--cardiovascular diseases, chronic respiratory diseases, cancers, and diabetes--by 25% from 2010 levels by 2025 (referred to as 25×25 target). Targets for selected NCD risk factors have also been agreed on. We estimated the contribution of achieving six risk factor targets towards meeting the 25×25 mortality target. METHODS We estimated the impact of achieving the targets for six risk factors (tobacco and alcohol use, salt intake, obesity, and raised blood pressure and glucose) on NCD mortality between 2010 and 2025. Our methods accounted for multi-causality of NCDs and for the fact that when risk factor exposure increases or decreases, the harmful or beneficial effects on NCDs accumulate gradually. We used data for risk factor and mortality trends from systematic analyses of available country data. Relative risks for the effects of individual and multiple risks, and for change in risk after decreases or increases in exposure, were from re-analyses and meta-analyses of epidemiological studies. FINDINGS If risk factor targets are achieved, the probability of dying from the four main NCDs between the ages of 30 years and 70 years will decrease by 22% in men and by 19% in women between 2010 and 2025, compared with a decrease of 11% in men and 10% in women under the so-called business-as-usual trends (ie, projections based on current trends with no additional action). Achieving the risk factor targets will delay or prevent more than 37 million deaths (16 million in people aged 30-69 years and 21 million in people aged 70 years or older) from the main NCDs over these 15 years compared with a situation of rising or stagnating risk factor trends. Most of the benefits of achieving the risk factor targets, including 31 million of the delayed or prevented deaths, will be in low-income and middle-income countries, and will help to reduce the global inequality in premature NCD mortality. A more ambitious target on tobacco use (a 50% reduction) will almost reach the target in men (>24% reduction in the probability of death), and enhance the benefits to a 20% reduction in women. INTERPRETATION If the agreed risk factor targets are met, premature mortality from the four main NCDs will decrease to levels that are close to the 25×25 target, with most of these benefits seen in low-income and middle-income countries. On the basis of mortality benefits and feasibility, a more ambitious target than currently agreed should be adopted for tobacco use. FUNDING UK MRC.