Prescribing 'warmth' for the winter

How being cold has a serious effect on new and existing health problems
25 November 2022

Interview with 

Christof Schweining, University of Cambridge


A close up of a thermostat dial


In the past, doctors used to prescribe a hot bath for some disorders, but now in some areas history is almost repeating itself with practitioners writing prescriptions for heating for patients with conditions that get worse in the cold. In an initial trial, the Warm Home Prescription pilot paid to heat the homes of 28 low-income patients to avoid the cost of hospital care if they became more ill. Those running the trial said it achieved such good results they plan to expand it to 1150 homes. So why is heating a wonder drug, and do the figures stack up? Cambridge University physiologist Christof Schweining knows all about how we keep warm and stay cool - he often puts his knowledge into practice as a highly successful marathon runner…

Christof - Well, I wondered exactly the same thing just before I came down to meet you. So I did a quick calculation on my trusty spreadsheet. So I looked up a patient in hospital for a single day, at least in A&E is about 400 pounds. And if you assume that you could target the people who want to have their homes heated appropriately, maybe you could stop 10% of the emissions. And then you imagine that perhaps if you were to get ill and be in an unheated house and get ill, that you would have a stay of perhaps two weeks or three weeks in hospital. Then it's worth, at least over the four months of winter, paying a hundred to maybe two hundred pounds a month off a fuel bill to do that. So I think it actually does make sense. I think it all depends on how well you can target this as a treatment.

Chris - What's the rationale though, for making people warmer in winter and that reducing their risk of disease? What's the link between being cold and getting health problems?

Christof - There are so many links going on here. One of the big links, which isn't talked about often enough, is the effect of, for instance, lying down in bed to stay warm over a prolonged period of time. That's an absolutely massive detraining stimulus. So imagine you've got somebody who is aging and relatively unfit. They've got some underlying disorder as well. If that person detrains as a result of lying down not being exposed to a gravitational field and also not performing exercise, just routine daily exercise, then they really do risk, at the end of a winter period or at least several weeks on into this bedrest, becoming so unfit that they struggle to deal with any kind of exacerbation of an underlying illness.

Chris - So this would be people retreating to bed early because it's warmer in bed than it is in the living room.

Christof - Oh, absolutely. I know I've just bought an electric blanket. Being in bed is a wonderful thing, but it's awfully a dangerous place to be really. Old people are particularly at risk here because the ability to sense your internal temperature reduces and your ability also to control the blood flow to your periphery, really to lock off the blood flow from the periphery to keep it centrally in the well insulated area that declines with age. So you've got old people and ill people who've got low maximal rates of aerobic work. They've got a compromised ability to sense their core temperature and also a compromised ability to restrict the blood flow to maintain the core body temperature. All of this adds together into a scenario where even if you don't have an acute serious illness at the point at which you take to bed, you may well end up at the end of a period in a position where you might need hospital care.

Chris - The rates of things like heart attacks and strokes also shoot up in winter. Can that be explained on the basis of what we know about how the body handles temperature?

Christof - Certainly. So there are some really simple acute effects that are well known. So when you get cold, you peripherally vasoconstrict, so you reduce the blood flow to the periphery. This pushes the blood centrally and as a result of that, you also get a rise in arterial blood pressure as well and somewhat of a thickening of the blood, so a haemo concentration. And all of that places a stress on the heart, which of course can exacerbate any kind of cardiovascular disorders. But there is some disagreement here as to exactly what the drivers are. So there are lots of things that go on when the weather gets cold and you take to bed, you become potentially a little bit depressed, a little bit less likely to exercise, maybe less likely to take care of yourself, to eat appropriately and indeed to drink as well. So all of these things add together to produce cardiovascular stress.

Chris - Do we see then the countries where it is warmer and warmer in winter, that they don't have this surge in winter mortality? Because that's the thing we see, isn't it? Every winter we see this so-called surge in excess mortality. Now some of that will be things like the flu, but many argue it is the cold that is killing people.

Christof - Ah, well this is interesting because you've caught me here on a set of data that I don't have. So I don't know whether the equatorial regions really suffer the same set of problems, but what's certainly true is if you look at different sets of societies, some are certainly much better adapted to cold weather. So if you look at the Scandinavian countries in particular, the infrastructure is such that the cold weather really doesn't present a problem. We are sort of stuck in the middle in that we have winters, which are sometimes quite cold, and so like the leaves on the line, we don't tend to take the necessary set of precautions.

Chris - You preempted where I was going with that, because I was going to say, well, there are many countries where it is much colder in winter than seven degrees today here in Britain, and we are not seeing the sort of surges in mortality that we see here. So it must be all relative then.

Christof - Oh, absolutely. I mean the bus stop is a really wonderful example. If you have a public transportation system aimed at a set of individuals who are more likely to be at risk from cold weather and then you don't have a regular bus service, you risk leaving them sat stationary in cold conditions for a prolonged period of time. And that really then presents a major acute risk. So something as simple as having a regular bus timetable that arrives on time, we just don't think about that. But things like that can be absolutely critical when looking at the risk of cold weather.


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