Intended for healthcare professionals


Population ageing: the timebomb that isn’t?

BMJ 2013; 347 doi: (Published 12 November 2013) Cite this as: BMJ 2013;347:f6598

Re: Population ageing: the timebomb that isn’t?

Spijker and MacInnes’ paper is an important contribution to reframing the debate on ageing in the United Kingdom and, in particular, in urging us to rethink our notions of a ‘demographic timebomb.’ There are, however, three areas in which the paper can be found lacking.

Firstly, I feel that the paper does not give adequate credit to Sanderson and Scherbov who, in their papers variously published in Science and Nature, have proposed – and calculated for the United Kingdom – dependency ratios based upon the notion of a remaining life expectancy of 15 years. In other words, the same overall message of this paper was arrived at Sanderson and Scherbov’s 2010 Science ‘Policy Forum’ paper where they showed that such a ‘Prospective Old Age Dependency Ratio’ [POADR] for the United Kingdom – defined as ‘the number of people in age groups with life expectancies of 15 or fewer years, divided by the number of people at least 20 years old in age groups with life expectancies greater than 15 years’ – rose from 0.19 in 2005-10 to just 0.22 by 2045-50. Again, this increase is slight compared to their reported ‘traditional’ Old Age Dependency Ratio [OADR] based upon populations aged 18-64 and 65+, which was projected to nearly double over the same period from 0.27 to 0.51.

Spijker and MacInnes’ paper does, however, add to the work of Sanderson and Scherbov by adding in rates of employment to the denominator (although a similar mode of remeasurement coined the ‘Pensioner-Worker Ratio’ was performed by Bongaarts in 2004, again for the United Kingdom). However in contemporary Britain, the nature of the job market is such that defining being ‘in’ and ‘out’ of the labour market as a binary construct is fraught with difficulties. The recent debate over so-called ‘zero-hour’ contracts is a case in point. In this sense, the addition of an employment variable somehow misses the first main point of calculating a prospective dependency ratio – namely that by focussing on the relative size of the population who are here defined as ‘truly dependent’, or within the last 15 years of life, demographers are able to present policymakers with a new ‘upper bound’ of the population which is currently labelled as ‘dependent’ at age 65. Not only does this allow for better state- and private-sector financial planning, but it also allows for a more proactive policy agenda towards maximising the accrued human capital of the older, non-dependent population. This should have been more adequately recognised in the paper.

Finally, readers of the BMJ may have been frustrated by the somewhat arbitrary use of a 15-year ‘end of life’ interval during which the population is deemed as ‘dependent’ as employed both in this paper and by Sanderson and Scherbov. While Sanderson and Scherbov – and myself for East Asia – have attempted to justify this ‘cut off’ point, it is possible to move beyond this and define a ‘dependent’ population more adequately. To this end, Sanderson and Scherbov have defined a further measure termed the ‘Adult Disability Dependency Ratio’ [ADDR]. This is defined as the number of adults at least 20 years old with disabilities, divided by the number of adults at least 20 years without them. This measurement also takes into account increasing life expectancies. In their analysis they used data from the EU-SILC, the leading comparative survey on disabilities across Europe, and employ the survey’s hybrid biosocial measurement of disability, namely that it should be ‘strongly limiting’ and persistent, and that it includes both physical and mental problems. As such, in pure fiscal terms, if we associate ageing with increased prevalence of such a population, this is where the ‘timebomb’ would be truly located. However, Sanderson and Scherbov find that for the United Kingdom, this ADDR stays completely constant at 0.10 from 2005-10 to 2045-50. As they conclude, ‘although the British population is getting older, it is also likely to be getting healthier, and these two effects offset one another. Not only does the ADDR increase less rapidly than the OADR, it also increases less rapidly than the POADR, so that adjusting for the likely future path of disability rates does not simply replicate the results of adjusting aging measures for changes in longevity.’

The United Kingdom desperately needs an integrated, holistic strategy for dealing with an ageing population. This includes both improved management in health and social care, as well as a cultural shift in the perception of the roles which the population at older ages play in society. Spijker and MacInnes’ paper plays an important role in starting to shake the ‘fear’ out of the debate. However, when we are calculating ageing and dependency in an era of improved health and longevity – but also of challenging labour market conditions and fixed popular notions of life expectancy and retirement – it is critical to both use more specialised data, and to communicate better what we truly mean by ‘dependent.’ This can help us better plan for both caring for those who need it most, and for releasing the potential of those who are able/willing to be counted in what we traditionally think of the ‘denominator’ group of those active in the labour force and wider society.

Perhaps, even, it might be better to stop using the words ‘old’ and ‘elderly’ altogether.

Competing interests: No competing interests

21 November 2013
Stuart A Basten
University Lecturer
Department of Social Policy and Intervention, University of Oxford
32 Wellington Square, Oxford, OX1 2ER