Thursday April 30 2015
Life expectancy is expected to rise thanks to improved public health
"Life expectancy is rising faster than thought, with 90 expected to become the norm in some affluent areas of the country by 2030," The Guardian reports. The same predictions led the Daily Mail to warn of a "life expectancy timebomb".
A new modelling study looking at trends in life expectancy estimated that male babies born in 2030 could live to an average of 85.7 years, with females living an average of 87.6 years.
The study also flagged up the potential effects of health and socioeconomic inequalities on life expectancy. For example, it estimated life expectancy in the affluent London borough of Kensington and Chelsea would be five to six years higher than the working class area of Tower Hamlets.
It remains to be seen if the increase in life expectancy would be a blessing or a burden. Elderly people contribute to society in many meaningful ways, such as helping out with childcare or volunteering for charity work. But they may also have complex health needs that could require significant resources to treat.
Assuming the model is accurate, the study produces some interesting results about trends in life expectancy and inequalities, and how they may change over time.
Where did the story come from?
The study was carried out by researchers from the department of epidemiology and biostatistics at the School of Public Health and MRC-PHE Centre for Environment and Health, the UK Small Area Health Statistics Unit, Imperial College London, Northumbria University, and GlaxoSmithKline. It was funded by the UK Medical Research Council and Public Health England.
The study was published in the peer-reviewed medical journal, The Lancet. It has been made available on an open-access basis, so it is free to read online.
Most of the media reported the results of the research well, although they did not question the accuracy of the predictions much. Different outlets focused on different aspects of the research.
The Daily Telegraph and the Mail focused on the headline figure that the study predicted higher life expectancies than official estimates. In its headline, the Telegraph claimed people would live "up to four years longer" than official estimates, although the study shows a difference of 2.4 years for men and one year for women.
BBC News highlighted the narrowing gap between men and women's life expectancies, while The Guardian and The Independent were more concerned with the widening gap between rich and poor.
What kind of research was this?
This modelling study analysed death rates and population data for 375 districts of England and Wales. Researchers used the data to construct mathematical models to predict life expectancy from 1981 to 2030 for each of the districts, looking at men and women separately.
The study aimed to give reliable district-level information about life expectancy to help with future planning for health, social service and pension needs. The figures are all averages for the districts and cannot be used to predict individual lifespans.
What did the research involve?
Researchers looked at records of deaths in England and Wales between 1981 and 2012 by local authority district. They combined this with population data to develop five statistical models that could predict future death rates and life expectancy.
The researchers tested the models to see which best predicted actual death rates during the last 10 years of the data, then used the best-performing model to predict future life expectancy at the local and national level.
The data in the study came from the Office for National Statistics. The models incorporated features of death rates in relation to people's age, trends of death rates in people who were born within or close to the same five-year period, changes to death rates over time, and by local area.
The test of the five models found one model, which gave greater importance to trends in those born within adjacent time periods, worked better than the others, with forecast errors of 0.01 years for men and women.
This model was best able to predict death rates for 2002-12 using the first 21 years of the data. The researchers therefore chose this model to predict life expectancy from 2012-30.
While the geographical areas of the districts remained the same over the study, people living in these areas obviously change. The researchers looked at trends for each district, including birth rates and migration, so they could factor this in.
They looked at how relative levels of deprivation for each district affected the mortality rates and life expectancy. Taking account of all this data, they then predicted how life expectancy at birth could change from babies born in 2012 to babies born in 2030.
Rates for men and women were calculated separately, as life expectancy differs by gender. As far as we can tell from the paper, the analysis was done using reasonable assumptions about population trends.
What were the basic results?
The study found life expectancy in England and Wales is expected to continue to rise from the 2012 average of 79.5 years for men and 83.3 for women, to 85.7 (95% credible interval 84.2 to 87.4) for men and 87.6 (95% credible interval 86.7 to 88.9) for women by 2030.
This is higher than predictions from the Office of National Statistics. However, this will come at the cost of increasing inequality between districts.
Improvements in life expectancy from 1981-2012 varied a great deal between districts. In 1981, men in districts with the best life expectancies could expect to live 5.2 years longer than those in the areas with the lowest life expectancies (4.5 for women).
By 2012, this had increased to a difference of 6.1 years for men and 5.6 years for women. The study says this trend is expected to accelerate, so that by 2030 the difference in life expectancy between the best and worst districts could reach 8.3 years for both men and women.
Most of the districts with the lowest life expectancies now and in 2030 were in south Wales and the northeast and northwest of England. The areas with the highest life expectancy were mostly in the south of England and London. However, London districts varied from the highest to the lowest life expectancy levels.
The gap between men and women's life expectancy is expected to shrink further. It has already shrunk from 6 years in 1981 to 3.8 years in 2012, and by 2030 it could be only 1.9 years. In some areas, there may be no difference between men and women's life expectancy at all.
How did the researchers interpret the results?
The researchers say their results are a more accurate prediction of how life expectancy will increase than official figures, and are the first to look consistently at changes in life expectancy at the district level over a long period of time.
They say the increase is likely to be the result of better survival in people over the age of 65. They say men's life expectancy will rise faster than women's, partly because of the effect of social trends such as smoking among middle-aged and older women.
The researchers claim the data will allow local authorities to plan better for the future, especially as much health and social care is now the responsibility of local areas. However, they also say the figures provide a warning that inequality in England and Wales will continue to rise.
This analysis of population data provides some fascinating information about how life expectancy has changed over the past 30 years, and how it may change in the future.
It found life expectancy for men and women will continue to rise. However, it also found the existing trends of the difference in life expectancy between different districts will continue to rise, which is of concern.
Although the data shows more deprived areas have seen less of an improvement in life expectancy, the study cannot inform us what factors are responsible for the differences in life expectancy.
There is one big limitation of any study that predicts life expectancy in the future: the figures are always based on trends from death rates in the past, and assume that past trends will continue into the future.
These types of studies cannot account for unexpected events or major social changes that could have a huge effect on life expectancy. For example, they can't build into their models the potential for unlikely events such as a big natural disaster, changes within the healthcare system, or even a major health breakthrough, such as a cure for heart disease or cancer.
It's worth remembering, too, that life expectancy figures represent the life expectancy of a baby born in that particular year. So the life expectancy figures for 2012 don't represent life expectancy for adults alive in 2012, but for babies born that year. This means the figures for 2030 don't yet apply: they are only predictions for babies born in the future.
The study can't be used by individuals to predict how long they may live, but it does provide useful data to plan for pensions and health and social provisions in the future.
If you are keen to live to 2030 and beyond, your best bet is to take steps to reduce your risk of the five leading causes of premature death:
Read more about the top five causes of premature death.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.