March 25, 2019

expert reaction to study looking at sitting down and death

Research published in Journal of Epidemiology & Community Health demonstrates that prolonged sedentary behaviour causes a considerable burden to the NHS in the UK.

Prof Naveed Sattar, Professor of Metabolic Medicine, University of Glasgow, said:

“I simply don’t believe there is anything bad about sitting down per se.  Other stronger studies show that as long as you remain active in other parts of your life, sitting down for parts of the day, whether at work or at home, is not an issue that leads to adverse health.  So people should not worry about sitting down at work if that’s what they have to do.  The better message to communicate is people should aim to accumulate more activity commuting to their works or during their evenings.  Even adding an extra 1000 steps per day is a reachable target for most if they feel they are not getting enough activity.

“Part of the issue with studies including this one is that those with illness or sub-clinical illness tend to sit more because they feel tired – in other words, being unwell makes people sit more rather than the other way around, so much of the research this report is based on fails to consider what is called ‘reverse causality’ whereby the bad outcomes cause more sitting rather than or much more than the reverse.  That said, helping people become more active is a better message and this could include short walks, or anything that involves moving around or using some muscles.  Activity equals better body and minds, and helps people stop putting on weight.”

Dr Gavin Sandercock, Reader in Clinical Physiology (Cardiology) and Director of Research, University of Essex, said:

Does the press release accurately reflect the science?

“Yes.

Is this good quality research?  Are the conclusions backed up by solid data?

“Yes kind of – the data are modelled so they are not ‘real’ deaths and the authors have to make a lot of assumptions.

How does this work fit with the existing evidence?

“Yes – we know sitting too much can be bad for health but this is the first really detailed look at the cost of problem in the UK.

What are the implications in the real world?

“The implications are interesting.  The move from manufacturing to a predominantly service-based industry means that people sitting at desks are now the backbone of the UK economy.  Sitting less might save some lives and cost the NHS less but, because we have created a sitting-based economy, there are likely to be costs associated with interventions to reduce sitting-time in the workplace.

“The ‘bang for your buck’ of reducing sitting time is pretty small in terms of health benefits – you actually have to reduce sitting time by several hours each day to see noticeable improvements in health.  In contrast – getting people to be more physically active has much bigger effects.

“Another reason it might be better to concentrate on activity rather than less sitting is that active people seem to be able to sit almost as much as they like and still be healthy.  A study of over a million adults found ‘High levels of moderate intensity physical activity (i.e., about 60–75 min per day) seem to eliminate the increased risk of death associated with high sitting time’¹.

“OF COURSE, the best lifestyle is one including lots of activity and as little sitting time as possible – but reducing sitting time by the necessary amount to have real public health benefits just might not be useful.

“That same study¹concluded ‘these results provide further evidence on the benefits of physical activity, particularly in societies where increasing numbers of people have to sit for long hours for work’.

Is there any overspeculation?

“Maybe – if the benefits or MORE activity are weighed against those of ‘less sitting’ then the former is more practical, achievable and likely to have more benefits – the two things (sitting and being active) are not the opposite of one another but should be considered together.”

Prof Kevin McConway, Emeritus Professor of Applied Statistics, The Open University, said:

“The researchers have worked carefully on establishing the numbers they are publishing, and have put together data from an impressive range of sources.  One could perhaps nit-pick about some details, but they are surely in the right ball-park at least.  However, my concerns are not about the numbers themselves, but about their interpretation.

“The researchers conclude that the direct costs to the NHS of “prolonged sedentary behaviour” – that is, people spending at least six of their daily waking hours sitting or lying down – amount to at least £0.7 billion a year.  That sounds like a lot, but is it really?  We need a basis for comparison.  Total expenditure on the NHS across the UK in 2016/17, the year the researchers used for their calculations, was about £144 billion¹.  The estimated direct costs of prolonged sedentary behaviour are about half of one per cent of that total.  Looking at it another way, the UK population at the time was just below 66 million, so the direct costs of prolonged sedentary behaviour work out at about £11 per person in a year.  However the total NHS spend per person was almost £2,200 per person in that year.

“Still, wouldn’t it be better to get rid of sedentary behaviour so that we could spend that £11 per head on something else?  Well, maybe, but we’ve got to think about whether it would actually be available for spending if we could wave a magic wand and get everyone to spend less than 6 sedentary hours a day.  An aspect of the human condition is that we all have to die of something eventually.  So some of the people who are saved by our magic wand from a heart attack, stroke or cancer related to sedentary behaviour might, unfortunately, die of something else that actually costs the NHS more money than their sedentary-related death would have cost.  We can’t tell from these numbers – and anyway, is looking at these direct costs a sensible way of approaching the question?  As the researchers point out, their total probably omits some direct NHS costs anyway, and it can’t take any account of costs to the affected people and their families, to employers, in state benefits, or many other possible costs.  Overall, I find it hard to see the usefulness of the £0.7 billion number.

“The researchers’ calculation of the number of deaths that might be avoided, if there were no prolonged sedentary behaviour, is a bit more useful in my view.  Again, I think we need some context – the authors estimate that there were about 70,000 such deaths in 2016 [the corrected figure], which sounds like a lot, and is indeed almost 12% of the almost 600,000 total deaths that took place in the UK that year.  But the diseases involved have multiple causes, and it’s difficult to know whether they are best avoided by reducing sedentary behaviour or by some other changes.  Also, though avoiding these deaths would be good, just how important it is would depend on how much longer the people in question would have lived anyway.  We all die.  Would these people have lived, on average, another few months or several decades if they had got up of their chairs more often throughout their lives?  These results can’t tell us.  There are other approaches, such as calculating the ‘years of life lost’ from a potential cause, that would have been much more helpful.  And even taking the 70,000 death figure, the researchers point out in their research paper that it’s unrealistic to expect that all prolonged sedentary behaviour could be eliminated.  They provide figures that they describe as ‘more realistic’, for example for the position if the numbers of people sitting around too much were reduced by 50% or 10% rather than reduced to zero.  With a 30% reduction, for example, the estimated number of deaths would be about 21,000.  Still sounds like quite a lot, but obviously much less than 70,000.

“None of what I’ve written should be taken to mean that I don’t think action should be taken to reduce sedentary behaviour.  There are many reasons why such action is important, and there is already good evidence for these reasons.  But I’m not sure that these new calculations add much to the debate about priorities.”

*Comment updated at authors request on 26/03/2016 09:36.

‘Direct healthcare costs of sedentary behaviour in the UK’ by name of first author et al. was published in the Journal of Epidemiology & Community Health at 23:30 UK time on Monday 25 March 2019.

Declared interests

Prof Naveed Sattar: “No COI.”

Dr Gavin Sandercock: “No conflicts of interest to declare.”

Prof Kevin McConway: “Kevin McConway is a Trustee of the Science Media Centre.”