The first international study to quantify the causes and patterns of death in children over 5 years old from 50 countries over the second half of the 20th century shows that, in a reversal of historical mortality patterns, death rates in young people (15 years) are now higher than in children (1 years) across most high- and low-income countries. In particular, death rates in young men (15 years) are now two to three times higher than in boys (1 years). The majority of deaths in young people are now due to injury, limiting improvements in mortality in this age-group over the past 50 years to just half that of children.
These and many other findings, published in an Article Online First in The Lancet, highlight the lack of interventions and resources directed to tackling the contemporary health problems faced by young people. The authors hope their findings will promote a new global focus on the health and causes of death in adolescents and young adults.
"Mortality in young adults aged 10 years has proved less responsive to the epidemiological transition [of the past 50 years], and to alliances and interventions, than has early childhood mortality (1 years). These trends are likely to continue because mortality in children younger than 5 years is expected to decline further, and injury-related mortality is expected to increase in the next 25 years with the continuation of the epidemiological transition in developing countries", explain Russell Viner from the UCL Institute of Child Health, London, UK and colleagues.
A strong international focus on reducing mortality in children under 5 years has not been matched by a similar response in older groups, even though more than two-fifths of the world's population is in the 5 year age group.
In this study, the authors used the WHO mortality database, to analyse mortality data for 50 countries with a range of incomes between 1955 and 2004. Patterns of mortality were investigated by cause of death (communicable and non-communicable diseases and injury), age group, and sex. To analyse changes in morality, they calculated death rates averaged over three 5-year periods (1995, 1978, and 2000).
Findings showed that in the 1950s, mortality in the 1 year age-group greatly exceeded that of all other age-groups in all regions studied. But in the 50 years up to 2004, death rates in children aged 1 declined by 80% mostly due to reductions in deaths from infectious disease.
In contrast, reductions in mortality in young people aged 15 years were only about half that in children, largely because of increases in injury-related deaths, particularly in young men. Indeed, by the start of the 21st century, injuries were responsible for 70% of all deaths in young men aged 10 years in all regions studied.
The research also showed that violence and suicide have become key causes of death in young people, responsible for a quarter to a third of deaths in young men aged 10-24 years in all regions studied by 2004.
The authors point out: "The high injury burden in young people means that they are particularly affected by the persistent low global investment in non-communicable diseases and injury relative to global disease burden."
They conclude: "Future global health targets should include the causes of death in people aged 10 years, and should extend beyond HIV infection and maternal mortality to include injury and mental health."
In a Comment, Michael Resnick from the University of Minnesota, Minneapolis, says: "The profound health and social changes that have accompanied economic development and urbanisation are particularly toxic for young people in both high-income and low-income settings."
He adds: "Breakthroughs in medical discovery and service delivery are incomplete responses to the health threats faced by young people, in view of the profound role of socioeconomic conditions, access to education, and opportunity as determinants of life trajectory...Adolescence represents the second crucial window for prevention and health promotion. Effectively addressing the social determinants of health in the second decade of life can interrupt the processes by which disadvantage becomes adverse destiny, including premature mortality."