The global health impacts of population ageing

How will changes in population transform the world’s ability to meet the challenges that lie ahead for society and our healthcare services? That was the central question underpinning Prof Sarah Harper’s illuminating keynote address, as she opened the 4th European Healthcare Design Congress in London earlier this week (11 June).


Professor of gerontology, and director of the Oxford Institute of Population Ageing, Prof Harper considered how our populations are likely to evolve according to demographic trends in fertility, mortality and migration, and their national and global impact both on society and our healthcare systems.


After introducing a packed auditorium to some key trends on population size, consumption, density and distribution, she homed in on the heart of her work at the Oxford Institute: that of the ageing population.


undefined - undefinedDissecting the patterns on a global scale, Prof Harper outlined how in two-thirds of the world’s countries, women have reduced their fertility to roughly replacement level. In most sub-Saharan African countries, however, women are still having, on average, between four and eight children – and it’s predicted that unless African women are helped to reduce the number of children to whom they give birth, the world’s population could double and reach 15 billion by the end of the century. 


“For the very first time, the growth in world population is being driven as much by longevity as it is by fertility,” said Prof Harper. “In other words, [the elderly] are, demographically, not dying ‘on time’.”


Looking at ageing populations according to national wealth, the trends would indicate some very powerful dynamics are under way.

In low-income countries, there are currently huge numbers of children, although their number has been in slight decline since 2010. Moreover, these countries are beginning to see massive growth in their working-age population.


In the middle-income countries, decline in the number of young dependents is already occurring, while there is tremendous expansion in young people and an increase in the number of older dependents. It remains to be seen, said Prof Harper, if these countries are able to convert their youth bulges into a “demographic dividend”.


But high-income countries are seeing a dramatic reduction in child dependents at the same time as an increasing number of older dependents, with a real squeeze on the income-generating workforce.


“The only way high-income countries can balance their population structure is through migration,” said Prof Harper.


Population shifts and their impact on life expectancy

Against these dramatic shifts in population structure, the relationship with life expectancy promises to be profound.


In Europe, 150 years ago, half the population was dead by age 45, but today, half the population will make it to 80. In the middle-income countries, this transition from huge infant and maternal mortality, to pushing back death into the later ages is ongoing.


“Sadly, in the lower-income countries, typically sub-Saharan Africa, there is massive maternal, child and infant deaths, and deaths still across the life course,” said Prof Harper.


Highlighting two recent studies in the Lancet, she moved on to present some evidence of how long we’re all likely to live. According to a study last year, by 2030, women in South Korea are likely to have a life expectancy at birth of over 90 – a threshold that few, if any, demographers ever believed would be surpassed.


Another Lancet study looked at the oldest age at which 50 per cent of a birth cohort would still be alive. Within a 2007 birth cohort, it was found that half of the population in Japan is expected to reach 107; in France and the US, the figure is 104, and in the UK, 103.


“There is a general acceptance among demographers that half of the babies now born in Europe will make it to 100,” said Prof Harper.


But a long life – and, in particular, a long, healthy life – is not necessarily going to be enjoyed by everyone. Inequality in society means that those with low incomes, who are more likely to live in more deprived areas and have unhealthy lifestyles, will not enjoy the same benefits in later age, as people on high incomes.


Death across the life course

“What we’re really beginning to understand is that health across the life course is probably the biggest driver to our health in late life,” explained Prof Harper. “It’s not what we do in our 50s and 60s but it’s health across the life course [that’s key].”


Commenting on findings from her own work, based on Office for National Statistics data in England, she continued: “The extraordinary thing is that if you’re living in one of the most deprived areas of the UK, at 65 you’ll probably make it across your 70s, but almost your entire 70s will be in ill health. If you’re living in the most affluent area, you’re going to make it into your late 80s, and your entire 70s are going to be in good health.


“It’s not about life expectancy,” she summarised. “It’s about healthy life expectancy.”


What’s more, obesity – widely considered to be one of the primary health challenges of the 21st century –is reducing life expectancy by only 1.4 years yet increasing disabled years by six.


Said Prof Harper: “The drivers of science and medicine that are keeping us alive for longer are also going to be keeping us alive in frailty for longer.”


Ending on a positive note, she offered a neat segway into a subsequent discussion on an example of the type of innovation that the private sector is currently undertaking to make health more affordable and accessible, by stressing that new technologies – in areas such as stem cell research, 3D printing, and nanotechnology – are likely to have a huge impact not just on individual longevity but also on the life expectancy of populations.


While using robotics and AI to care for its frail and elderly is something that Japan is tackling head on, Western societies are yet to truly grasp this issue, she suggested. Nevertheless, she added, these technologies could, potentially, sit right at the heart of health and social care policy in the very near future.