Elsevier

The Lancet

Volume 377, Issue 9783, 18–24 June 2011, Pages 2093-2102
The Lancet

Articles
Global burden of disease in young people aged 10–24 years: a systematic analysis

https://doi.org/10.1016/S0140-6736(11)60512-6Get rights and content

Summary

Background

Young people aged 10–24 years represent 27% of the world's population. Although important health problems and risk factors for disease in later life emerge in these years, the contribution to the global burden of disease is unknown. We describe the global burden of disease arising in young people and the contribution of risk factors to that burden.

Methods

We used data from WHO's 2004 Global Burden of Disease study. Cause-specific disability-adjusted life-years (DALYs) for young people aged 10–24 years were estimated by WHO region on the basis of available data for incidence, prevalence, severity, and mortality. WHO member states were classified into low-income, middle-income, and high-income countries, and into WHO regions. We estimated DALYs attributable to specific global health risk factors using the comparative risk assessment method. DALYs were divided into years of life lost because of premature mortality (YLLs) and years lost because of disability (YLDs), and are presented for regions by sex and by 5-year age groups.

Findings

The total number of incident DALYs in those aged 10–24 years was about 236 million, representing 15·5% of total DALYs for all age groups. Africa had the highest rate of DALYs for this age group, which was 2·5 times greater than in high-income countries (208 vs 82 DALYs per 1000 population). Across regions, DALY rates were 12% higher in girls than in boys between 15 and 19 years (137 vs 153). Worldwide, the three main causes of YLDs for 10–24-year-olds were neuropsychiatric disorders (45%), unintentional injuries (12%), and infectious and parasitic diseases (10%). The main risk factors for incident DALYs in 10–24-year-olds were alcohol (7% of DALYs), unsafe sex (4%), iron deficiency (3%), lack of contraception (2%), and illicit drug use (2%).

Interpretation

The health of young people has been largely neglected in global public health because this age group is perceived as healthy. However, opportunities for prevention of disease and injury in this age group are not fully exploited. The findings from this study suggest that adolescent health would benefit from increased public health attention.

Funding

None.

Introduction

In 2008, the worldwide population of young people aged between 10 and 24 years was more than 1·8 billion, the largest cohort ever, representing 27% of the population.1 This number is projected to peak in 2032 at about 2 billion, with 90% of these people in this age group living in low-income and middle-income countries.1 The size of this population makes their health status of interest, not only as a determinant of future population health, but also for social and economic development.2, 3 Adolescence is generally thought to be a time of good health, when disease burden is low.4 Although risk factors and the lifestyles that young people adopt might not affect their health during this period, they can have a substantial effect in later life5 and can potentially affect the health of future generations.6 For example, high patterns of physical activity that are adopted during youth and sustained thereafter are thought to have protective effects against the onset of cardiovascular diseases and type 2 diabetes.7

A report8 of the global and regional patterns of mortality for young people aged between 10 and 24 years recorded 2·6 million deaths in 2004 from a worldwide population of 1·8 billion in this age group. However, data for mortality only partly indicate disease burden because they do not show the conditions and behaviours that can lead to premature mortality and future disability—eg, the large burden that is associated with non-lethal mental disorders, which are common in adolescents and young adults.6, 9 Therefore, mortality data alone probably underestimate the potential importance of the contribution of adolescence to overall population health. An example is the onset of tobacco use and dependence, which typically occur during this period;10, 11 the prevention of even a small number of adolescents from smoking could substantially reduce the burden on future health and health systems.12 Other important determinants of health risk emerging during adolescence relate to eating patterns, physical activity and weight, sexual behaviours, use of addictive substances, and the use of motorised transportation.13, 14

This paper describes the global and regional burden of disease arising in young people aged 10–24 years, and the contribution of risk factors to that burden. It aims to provide policy makers with comparative data by cause, sex, and different age ranges from early adolescence to young adulthood. We have several specific aims: to describe all-cause and cause-specific disability-adjusted life-years (DALYs) across global regions for people aged 10–24 years with breakdown by 5-year age bands (10–14, 15–19, and 20–24 years); to describe incident disability caused by years lost because of disability (YLDs) across regions for this age group with breakdown by 5-year age bands as above; and to describe the main global and regional risk factors that contribute to incident DALYs for 10–24-year-olds (10–14 and 15–24 years).

Section snippets

Data collection

The data used in this analysis were from WHO's 2004 Global Burden of Disease (GBD) study.15 This study uses several data sources to quantify global and regional effects of disease, injuries, and risk factors on public health, and to provide a comprehensive and comparable assessment of worldwide mortality and loss of health attributable to these causes.16, 17, 18 Population data for 2004 were from the UN population division.1 Data were divided into three 5-year groups (10–14 years, 15–19 years,

Results

The overall burden for both sexes was much higher for children younger than 5 years (700 DALYs per 1000 population) than for other age groups (figure 1). We noted a substantial decrease in the burden for children aged 5–9 years. The burden slightly fell in those aged 10–14 years when compared with those aged 5–9 years, before increasing steadily from late adolescence to early adulthood and later life (figure 1). Overall, DALY rates were equal between sexes until adulthood, except for the

Discussion

Worldwide, young people bear a substantial burden of DALYs, both for YLLs and for YLDs, representing 15·5% of the total DALY burden for all age groups versus 18·5% in children younger than 5 years. This age group is the only one for whom DALYs were higher in women than men, notably in Africa and in southeast Asia. Africa had the highest regional rate of DALYs for those aged 10–24 years—2·5 times greater than in high-income countries. Differences in the causes of disease burden between

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