Sir Muir Gray: part 2
Watch the second part of Sir Muir Gray’s keynote speech from last year’s stakeholder conference. This video covers:
- how screening is recommended for different conditions
- the meaning of reasonable cost in screening
- what screening means
- questions for the future
There has always been concern about the harm from screening but if I read you the first sentence from the book on screening: “all screening programmes do harm”. This is from the book we wrote on the basis of our experience in screening called “Screening: evidence and practice”. The second sentence says “some do good as well and of these some do more good than harm at reasonable cost”.
Now actually that can apply to the whole of medicine. All healthcare does harm, some does good as well as harm and some does more good than harm. Whether it’s an operation or an MRI (Magnetic Resonance Imaging) or a drug or whatever, all medicine and healthcare does harm.
The issue for us in screening of course is that we’re not dealing with people who present with symptoms. You see, when you’re doing screening we’re screening whole populations; some of them have the disease and some don’t. Unfortunately the side effects of screening – and there are adverse side effects of screening as there are for all of healthcare – but we sometimes harm people who don’t stand any chance of benefiting. You see that’s quite different from, for example, the harm in an operation, that people who come to the operation all need the operation and they need to be fully informed but that’s part of the offer. There’s harm as well as benefit. Whereas we invite people to come in and some of them stand no chance of benefiting at all because they don't have the condition for which we’re screening. But when the screening test goes wrong and they’ve been harmed without any chance of benefit. So the contract is different and therefore the responsibility of people involved in screening is different. We have to be even more concerned about harm and more concerned about how we communicate that, but again as with the general principles of screening this is now relevant to the whole of healthcare, particularly in the age of the internet and the smartphone where members of the public expect access to the best current knowledge.
Decision making in screening
So I want to think a little bit more about what we learned about decision-making and the first issue is the policy decision – should we screen something or not screen it. In the early days of the National Screening Committee we usually based our decisions on systematic reviews of randomised controlled trials. And I remember I was going to a big meeting about prostate cancer screening and I received 4 phone calls on the way there and the phone calls are progressively more senior people up to someone saying the cabinet discussed this at Chequers at the weekend and they’re very concerned. I could picture all those men in the cabinet being uneasy about the discussion of prostate cancer screening. But fortunately we – the national R and D (research and development) programme as it was called then – had commissioned 2 systematic reviews. And you might say well that was very extravagant of them but the fact that we got 2 sets of people abstracting all the trials and literature and assessing the risks and benefits was very encouraging because we were primarily concerned about the harms.
Now when you’re enthusiasts for something you tend to be a little bit biased towards the positive so what we had to do then was to think about making sure that we from public health were seen as the people who looked at the negative side and we were often criticised for doing that. But that was the issue in policymaking – does it do more good than harm? And does it do that a reasonable cost?
Now what do we mean by reasonable cost and what do we mean by reasonable cost as we look ahead? Well reasonable cost is partly what we accept in terms of the NICE guidelines and NICE has been very helpful and they have a threshold of costs, costs per quality-adjusted life year. So in the good old days when the health service finance was growing like that then we could say well if it's above the line then we’ll introduce it and as I say for breast cancer screening we were given a budget to introduce it. Later we were not given budgets but we were given budgets for the pilots or to introduce something and to do the training but that was in a time of growth.
So what do we see when we look ahead? When you look ahead because you’re running it now, not me. Just to say a little about what I've been doing and partly trying to apply the methods of screening to the whole of the health service, I’ve also been developing something called NHS Right Care. And in Right Care we’re looking at the value, not value simply in cost per QALY, but value in terms of how much resource should be allocated to something because in a time when there is no more money, when we put resources into something we’re going to take those resources away from somewhere else. So we started getting into issues about relative value and the allocation of resources.
Deciding value of screening
So what I see happening in future are much broader discussions about the relative value of something. Let’s imagine some new screening test comes along for, shall we say, rheumatoid arthritis. Then we'll need to consider not only its effectiveness and its cost-effectiveness but we need to consider well how much we spend in rheumatoid arthritis at the moment and how does this compare with other things we might want to do for this population? This may have an impact on screening.
Let’s take a condition like breast cancer; some new development takes place for breast cancer, some new drug which is very effective and cost effective, some revolutionary drug, and it comes to decision makers and they decide well this is obviously of high-value. So where’s the money going to come from? In the old days it would come from the growth budget because health services were growing 4 or 5% a year. But in future it may be that existing screening programs will need to come into competition with demands for resources for that same group of people. And here when we’ve done this, not with screening but with other innovations, we always have the patients, the people in the room, and we ask them how did they see the relative worth of this compared with something else.
Now there’s firstly a decision about shall we introduce something. Secondly there’s a decision about how intensely we should screen the population. Now this picture here is the most important picture in healthcare. It’s a graph drawn by Avedis Donabedian in 1980. Avedis Donabedian invented the idea of structure, process and outcome. Previously people just thought about outputs, you how many operations were done, but he said no, it’s the outcomes that are important. Now what you can see from this graph here is that the benefits increase and then they flatten off. So in the steep part of the curve it’s once-in-a-lifetime cervical smear, 10-year interval, 5-year interval, 3-year interval, 1-year interval.
Unfortunately in healthcare, and again it’s not just screening, the more you do, the more money you put into a treatment, like hip replacement or knee replacement or anything, the harm goes up in a straight line. And if you subtract the harm from the benefit you get a j-shaped curve and he called it the point of optimality. What I found when I was doing screening was when anything went wrong the professionals involved, and the press usually, wanted us to do more – to invest more resources, for example, to shorten the interval between screening tests or to add an extra test. But you see from this graph here the more you do you may not get more value, actually the value may decrease. So all the time we want to be cautious in screening and we also have to be cautious in healthcare too. A lot of my work is involved in discussing these sorts of issues as they relate to care at the end-of-life, or elective surgery.
So think about the decision to introduce screening or not. Secondly, think about how intensely do we want to screen the population. And these are questions of value. And the third aspect of value, and what we call the triple value approach, is not to do with the population's allocation and use of resources but to do with the individual's perspective.
Now here, the cover of this book has got 2 sieves on it, 2 garden sieves. These come from the Pacific, I think, they were brought me as a present. And the word “screen” is a difficult word; you see in the 18th century the word screen meant something used for sieving coal or corn or flour and it's still used in that way. But in the 20th century the world “screen” came to mean something without any holes not at all like a television screen or a cinema screen and this meant that people started assuming that what we were doing was perfect. So women would try to sue us because they developed cervical cancer after they'd had a cervical smear test. But we were doing was just dealing with the screen, or the holes in the screen.
And the principle here is that we need to try to explain this to the public. I tried to do away with the word “screening”, actually, and in antenatal screening we talked a lot about risk assessment and this issue has come up a lot in the recent debates about the new test for a fetus with Down's syndrome. So we started to discuss things in a different way as to do with risk assessment – what is the probability that something good will happen and what is the probability that something not so good will happen?
Yet the word screen is still used as a sieve in one or two places. If you’re ever sitting on the train or driving down the road and you see these huge piles of gravel – aggregate they call it for some reason – then there’s a screening machine which you can see here which is shaking all the stones that have been dug out of the quarry to only let through the ones that are less than 5 cm or less than 3 cm. Because you see as you change the size of the holes, you change the proportion of positives that are identified and the number of false positives. The smaller the holes, if you want a hold back women for further investigation or babies for further investigation, you make the holes very small but that means you have a whole lot of false positives. If you make the holes bigger more of the affected individuals will fall through the holes but then there will be a lot less people adversely affected by screening.
So the word “screening” is still a useful word if you take the old-fashioned 18th century meaning of it as sieve – all we're trying to do is to separate people into higher risk groups and lower risk groups and as a consequence of that we said screening is everything up to the point of diagnosis. So when screening is advertised on the television then it’s not screening it’s just testing, initial testing, and this will really hit us as we start to see the human genome coming into clinical practice and people will want to screen for genetic variants and we must be very cautious about that. And this of course will greatly influences what we offer the individual and remember once in Belfast, one of my favourite cities, we had a great discussion – are people who come for screening are they patients or clients are consumers? And this doctor said “we we just call them punters, Dr Gray, let’s face it you’re taking a chance every time you come into the health service aren't you?” So punters they became. People are taking a chance, taking a risk, taking a probability.
And of course when we started this was before people like Gerd Gigerenzer, David Spiegelhalter, Steven Woloshin or Lisa Schwartz were writing so well about how you express probabilities to people. There wasn’t an evidence base for communication in the way that there is now. But I see the National Screening Committee is changing and is using information in a quite different way – and we didn’t do it 20 years ago but that’s because people hadn’t done the research and I recommend to you a book that Gerd Gigerenzer published called “Better doctors, better patients, better decisions”. It’s about probabilities. And poor people can handle probabilities as well as wealthy people. Someone said to me once “well social classes 4 and 5 can’t handle probabilities” and I said “well I know where I come from men can work out a 5 to 1, 7 to 2, 9 to 4 treble in their heads”, we just don't give them data.
So we’re moving now from screening, from the era of effectiveness and quality into the era of value and there are 3 aspects of value: allocative value – should we put money into screening or not, should we put more money into screening or not – technical value – are we increasing the intensity of screening and therefore going beyond the point of optimality – and finally personal value – what does the citizen think of the offer? How clear are they?
At one time I tried to change the payment system so that GPs weren’t paid for the number of cervical smears that they did but paid for the number of women who’d made a fully informed decision. But that proved just too difficult. And that’s something for the next generation, for you the leadership of screening in 2016, 2026 and 2036, these are the issues for you to tackle.
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