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Over-diagnosis: High Blood Pressure

Duration:
28 minutes
First broadcast:
Tuesday 21 August 2012

Dr Mark Porter asks whether doctors can try too hard in the early detection of disease and investigates the overdiagnosis of hypertension. This week he discovers that as many as 3 million people who have been told they have high blood pressure may not actually have it - could you be one of them?

  • Programme Transcript - Inside Health

    Downloaded from www.bbc.co.uk/radio4
    THE ATTACHED TRANSCRIPT WAS TYPED FROM A RECORDING AND NOT COPIED FROM AN ORIGINAL SCRIPT. BECAUSE OF THE RISK OF MISHEARING AND THE DIFFICULTY IN SOME CASES OF IDENTIFYING INDIVIDUAL SPEAKERS, THE BBC CANNOT VOUCH FOR ITS COMPLETE ACCURACY.


    INSIDE HEALTH

    TX DATE: 21.08.12 2100-2130

    PRESENTER: MARK PORTER

    PRODUCER: ERIKA WRIGHT


    Porter
    Hello and welcome to Inside Health. In today's programme we continue the theme of over diagnosis amid growing concerns that, in the quest for earlier detection, doctors are sometimes trying too hard - turning healthy people into worried patients. But what constitutes trying too hard? Well that depends upon who you ask.

    On the one hand there are the hawks who think we should be more aggressive in looking for and treating silent risk factors. Professor Bryan Williams is hawkish on high blood pressure.

    Williams
    We're trying now to move towards the philosophy that every stroke and every heart attack is potentially preventable. Why has somebody had a stroke when they're 50 and 60? It shouldn't be happening. Why has somebody had a heart attack? We have the information now to understand why these things can be prevented. So should we be looking at these as almost like a serious untoward incident?

    Porter
    And then there are the doves, like chest specialist Professor Alyn Morice who has a cholesterol level of nine, nearly twice the level regarded as healthy.

    Morice
    It is high, yes, do I take any treatment? No.

    Porter
    Did you consider taking treatment? What made you decide not to?

    Morice
    Well when the first trials came out showing that you could effectively lower cholesterol I did think well it sounds like a good idea and then more and more evidence has accumulated showing that the amount of benefit you get from treating just an isolated high cholesterol and ignoring all of the other things is a very poor way of judging it. Cholesterol is a risk factor but it's a minor risk factor, not a major risk factor. If you look at cholesterol the major drug used is Simvastatin and I'm sure many of your listeners are on this Simvastatin. Now Simvastatin's major side effect is muscle aches and pains. If you look at people who have marginally raised cholesterol and are put on a Simvastatin some of them get aches and pains and they don't exercise so much. So the side effect of the drug is actually causing the problem and so this is the nub of the argument - if you treat a large number of people with only a minor risk you're probably going to cause more harm than good.

    Porter
    As a clinician do you think in some areas we've become a bit over zealous in the quest for picking up people with abnormal signs rather than symptoms, we're looking for numbers all the time?

    Morice
    Well Mark I'd put it much stronger than that - we've become obsessed.

    Porter
    And it is you the public - or patients - who reap the benefits sought by the hawks, but who also suffer the side effects feared by the doves. Jeremy Green is associate Professor of History of Medicine at John Hopkins University and author of Prescribing by Numbers.

    Green
    I distinctly remember one man that I was treating for a very difficult to control form of high blood pressure and of course he had never suffered any symptoms from his high blood pressure. Once we got him on this regimen and had him under control he found that he became impotent, he lost erectile function, lost libido and we sat down and we talked about this and said well listen, you know, you are on a set of medicines for a condition that may or may not ever influence your life, we know that the medicines themselves are causing impotence, what do you want to do here, we don't need to aggressively pursue just the numbers for their own right. And he said, well you know I do need to do this, my father died of a heart attack when he was in his 50s, I'm in my 50s, I need to do everything I can to make sure I don't have a heart attack. So no I need to be on these medicines, I need to lower my risk. And then one breath later he asked me if he could have a prescription for Viagra.

    Porter
    Jeremy Green outlining an all too familiar scenario for Inside Health's Margaret McCartney I suspect. Margaret, you must see similar cases all the time where we're actually ending up treating a side effect of another treatment that we're giving.

    McCartney
    Absolutely and I think this is one of the increasing problems that we're finding as we get more and more guidelines offering to treat more and more risk factors and more and more pre-problems, we end up having people on more and more medications and we end up with a situation called poly-pharmacy, which really means that people are on an awful lot of tablets and pills. And the problem is as well that they interact with each other as well, so you're almost in uncharted territory in some ways that we end up being on far more medications I think than we envisaged when we started off trying to treat one thing.

    Porter
    And people in my experience are prepared to put up with side effects, or indeed to take more medication to mitigate them if the risks from whatever their problem is are high, so let's assume someone's got high blood pressure, very high blood pressure, very high risk of stroke then fair enough but what happens if you've got a borderline reading, whether it be cholesterol or high blood pressure, as most people do?

    McCartney
    Yeah I think the problem is that this takes into account really large chunks of the population, so there's millions of us really are sitting in these borderline groups. And of course if you're at lower risk - lower blood pressure making a lower risk of having a complication from that that really has to be weighed up against the side effects that you'll create by putting large amounts of the population on that drug. So even if you end up with a drug that's say got quite uncommon or rare side effects millions of people on them, the numbers will really start to stack up.

    Porter
    And let's put this in perspective because if you're at very high risk and you're on a drug that halves the risk of you having a stroke, let's say, then you're at very high risk then that's a significant benefit but if you're at tiny risk then half of tiny is small but your side effects are going to be the same, aren't they?

    McCartney
    Absolutely and I think that's the problem, you get one side effect and that side effect has an impact on your life and I'm sure you must see as well Mark in general practice what might seem like a minor side effect on paper, the list of things like nausea, vomiting, rashes, they can actually be huge life impairing, life sapping side effects people get and really alters the course of their life in a sort of downwards way.

    Porter
    Okay we'll come back to side effects a little bit later but just how low should these thresholds go - when does a normal blood pressure, for instance, become one that you and your doctor should worry about? Ray Moynihan is senior research fellow at Bond University in Australia and campaigns internationally to raise awareness of the dangers of over diagnosis.

    Moynihan
    Certainly there is evidence suggesting that hypertension or high blood pressure is another area where there is over diagnosis and there is a whole literature, in fact, on the over diagnosis of high blood pressure. And the thresholds, the cut offs, the diagnostic cut points, are continually being lowered in high blood pressure so that more and more people are being labelled. One of the, I think, most significant developments in recent times has been the creation of this new entity called pre-high blood pressure or pre-hypertension. Now that came out of a panel in the United States in the early 2000s and virtually overnight that panel created a new diagnostic category called pre-hypertension where essentially people with normal blood pressure were being labelled as if they had this. And there's a huge controversy within the specialist community that deal with high blood pressure about whether pre-hypertension is a real condition or whether it's a helpful category or whether in fact it's an unhelpful category that is labelling millions of healthy people as being sick.

    Porter
    High blood pressure, or hypertension, is defined as having sustained readings above 140 over 90 - with pre-hypertension being anything between that and 120 over 80, the lower figure generally associated with optimum health. And pre-hypertension is a new category that encompasses most people over 30. George Bakris is Professor of Medicine at the University of Chicago and was on the panel that coined the term.

    Bakris
    So this was really to educate the patient and to demand the physician do something and by the way it wasn't necessarily to prescribe medication, it was to educate the patient on lifestyle - sodium, potassium intake, exercise, reducing alcohol, smoking cessation - those kind of things.

    Porter
    Do the people who are told that they've got pre-hypertension consider this to be a disease, indeed do you consider it to be a disease?

    Bakris
    I do not consider it to be a disease, I consider it to be a risk. Hypertension, I believe, is a disease and I think there's pretty good evidence for that. Pre-hypertension is a state, it's an impending state that can be modified to alter the natural history of disease and that's really all it was meant to be.

    Porter
    And what about your patients George?

    Bakris
    Yes, so I think the patients, the ones that have read about it, think it is a disease, kind of a new disease and the good news with that is it prompts an explanation of what it really is and a clarification.

    Porter
    We may have good evidence that as your blood pressure increases above the 115 mark there's a gradual increase in risk factors like stroke and heart attack but do we have the evidence to show that intervening in this so-called pre-hypertension stage, either with lifestyle or in some cases medication, actually has a beneficial impact?

    Bakris
    Outcomes - no. There are no such data. Smaller studies defining changes in organ function - yes.

    Porter
    You were involved at very early stages in coining this term pre-hypertension are you happy now, looking back, on how it's come to be used, have you achieved your goal?

    Bakris
    Yeah, that's an excellent question. I wish I had data specifically to speak to it, there are some data that suggest that there has been more patient empowerment, there has been more request on the part of the patient for knowledge. But my experience is that the people requesting this are generally educated people, these are people with college degrees or professionals, they're the ones coming in - the so-called worried well - they're the ones requesting this. Many of the people at high risk, such as the minority populations - the blacks, the Hispanics - the ones that should be, they're not even aware of it and so no, I'm a little disappointed but I think something is better than nothing.

    Porter
    Do you think you may have worried the well even more, that they're now the worried, worried well?

    Bakris
    Yeah I'm afraid that we probably have done that, yes.

    Porter
    George Bakris. Margaret McCartney, this is another issue with concepts like pre-hypertension isn't it, I mean they target the wrong people.

    McCartney
    Absolutely and we've known about the inverse care loss since the 1970s when a GP called Gillian Tudor-Hart noticed that the least ill of the society attracted the most resources to them and the people who actually would have benefited the most from medical attention and care didn't seem to get it. And we're just doing exactly the same thing over and over again.

    Porter
    So here's a group with pre-hypertension, there's a group of people who are having their blood pressure carefully monitored, who may go on to develop problems later on but there's a whole other group who are never having their blood pressure even tested.

    McCartney
    Yeah absolutely and I think this is borne out time and time again. We keep offering these campaigns which are dependent on user take up or client or patient take up which results in the most motivated going along and these are probably the most motivated people to stop smoking or lose weight or do some exercise anyway.

    Porter
    And there's been another recent development in the on-going debate about the pros and cons of treating borderline blood pressure. A review published last week in the British Medical Journal found no convincing evidence that treating mildly raised high blood pressure did any good. Professor Jim Wright is Co-ordinating Editor of the Cochrane Hypertension Group in Vancouver responsible for the review.

    Wright
    We found that there is no evidence that the benefits outweigh the harms in this group. In the mild elevation range you're looking at at least a half of the people who are being treated for high blood pressure, so that's a large - that's a very large group.

    Porter
    I mean that'll fly in the face of medical convention. I'm a GP here in the UK and a large number of the people that we start on high blood pressure treatment have got blood pressure readings in that range and you're suggesting that there's no evidence of any benefit at all, in fact we might actually be harming them?

    Wright
    That's right and it was surprising to me as well but it shouldn't be because it's really just saying that we don't have the evidence in this group and that we should be doing more trials to find out what the evidence is. And in this case we were able to get evidence on around 9,000 patients from four trails followed for four to five years.

    Porter
    Because one of the criticisms might be that you wouldn't expect to necessarily see a major benefit in a short timescale like that, I mean when we're treating people's high blood pressure, particularly people with moderately raised levels, we're looking to prevent events that may be 10, 20 years down the line.

    Wright
    That's correct but even in the moderate to severe range we only had data for about five years and we were able to show a benefit in that group. It is true that you would like to have more data but the reality is there isn't more data.

    Porter
    Just to be clear - what we're saying here is that in mild elevation of the blood pressure we don't have, as yet, any evidence to suggest that intervention with drugs is helpful. It may be that it is helpful we just don't have that evidence as yet.

    Wright
    That's correct, yeah.

    Porter
    How do you think this is going to change clinical practice, if indeed it is?

    Wright
    I think it should change practice and it has changed my practice. When I'm dealing with people in this range now I don't have any problem in telling them that we don't have evidence that the benefits outweigh the harms of treatment. When I tell people that some patients say well I would like to not take any drug treatment and work on other things to keep my blood pressure under control, other patients might say I'm doing fine on the drug I'm taking and continue to take it. So I think it is our job to tell patients the fact that we actually don't know.

    Porter
    Jim Wright talking to me earlier on Skype.

    Blood pressure hawk, Bryan Williams, Professor of Medicine at University College London, does remain convinced - at least when it comes to protecting against an early stroke.

    Williams
    In terms of preventing stroke you probably can't have a low enough blood pressure. You're looking at levels of 110, 120 systolic which are definitely healthy. The risk begins to increase from that point on. In terms of heart attack I think getting below 140 over 90 is probably good enough. But stroke we could probably do more by lowering blood pressure further but the problem then is you get into mass treatment because we know that 25% of adults will have a blood pressure above 140 over 90, half of adults will have a blood pressure above 140 over 90 when they're over 60. So it's almost like putting fluoride in the water - the lower you take the threshold the more likely you are to treat huge numbers of people.

    Porter
    But is there a downside to treating someone for high blood pressure if they're pretty borderline?

    Williams
    There will be people who argue that whatever your blood pressure is if you lower it you lower your risk and that's almost certainly true, you will lower your risk of heart disease and stroke in particular. But the benefits to be gained if you're already at low risk are relatively small and that's an important concept. So I think that if your blood pressure's marginal and you have no other risk factors and you're otherwise very healthy the benefits from lowering your blood pressure in that context are relatively small and we should be focusing our attention on treating people who are a higher risk and getting them targeted. In terms of the offset of inappropriately treating people who have marginal risk, well some of the drugs do have side effects, not particularly severe like they used to be, they're very well tolerated in general but most patients wouldn't want to take drugs for the rest of their life if they didn't feel they were getting much benefit from it. And there's also the labelling of having a long term condition which influences insurance premiums and everything else. So it's not a trivial issue to get the diagnosis wrong or to label somebody inappropriately as hypertensive if their risk is relatively low.

    Actuality - Blood pressure reading
    Nurse
    Just need to wrap this round your arm.

    Porter
    Okay.

    But we do label a lot of people inappropriately and I could be among them, as I discovered when I had my blood pressure checked at Professor Alyn Morice's clinic at Castle Hill Hospital in Hull.

    Actuality
    Nurse
    Should be getting tighter about now.

    Porter
    I can feel it rising as I'm watching the figures.

    Nurse
    Try not to watch the figures, just try and relax.

    Morice
    Right.

    Porter
    [Laughing]

    Morice
    Well bad news Mark you're above the guideline recommendation here, so you're 161 over 103 - that's too high. Nothing to panic about and you should have that repeated over a matter of several months. If you are at that level each time you have it done then you do need treatment.

    Porter
    I need to be on treatment. You see I know that my blood pressure's about 132 over 80 something normally and has been for many years but this just demonstrates the problem - I'm sitting in an alien environment with a prof standing next to me with a microphone stuffed in my face and my blood pressure's gone up, that's normal.

    Morice
    It's got a term, it's called white coat hypertension and that's because when you're near a white coat your blood pressure goes up.

    Porter
    And I am far from alone - there are millions of people in the UK who have been wrongly labelled as having high blood pressure because of a similar reaction. Most of whom are on treatment they may not need. Bryan Williams.

    Williams
    If you look at a diagnosis of high blood pressure based on what we do at the moment in the doctor's office measurement we think about a quarter of people who have their blood pressure measured in the doctor's office and it's elevated and they're labelled as hypertensive, if they measure it away from the doctor's office it's actually normal and that's what we've been in the past calling white coat hypertension even though we don't wear white coats anymore.

    Porter
    If your 25% is right in terms of absolute numbers what sort of numbers are talking across the UK who might have been misdiagnosed using the current system?

    Williams
    Well we think it is right because we've done the systematic review and the second thing is there's a tremendous amount of data coming out from Spain now and they came to the figure of 23% that had a normal blood pressure despite having been diagnosed as hypertensive. So I think that figure is right. We think there's about 12 million people, adults, with high blood pressure in the UK, so if it's a quarter of them probably about three million people may have a blood pressure that's not as high as it was originally diagnosed when they were diagnosed.

    Porter
    And these are presumably the people at the lower end of the blood pressure readings, these are the people right on the borderline who are just tipped over by the readings they're having in their GP's surgery?

    Williams
    The majority would have what we would call stage one hypertension, in other words, as you say, within a few millimetres of mercury of the threshold which we arbitrarily set as a diagnostic threshold. But there are some who get a really quite marked alert response when they go to the doctor and actually have a completely normal blood pressure when they're away. And you'll have recognised yourself, as a GP, they're often the people who can't tolerate medication because they don't need it, you try and treat them and they come back and say they feel dizzy and they're feeling dizzy of course because when they their drugs away from the doctor's office their blood pressure's very normal, in fact low.

    Porter
    What sort of age do you think we should start looking for problems with high blood pressure, if you had to use a threshold and say everybody over the age of such and such an age should know their blood pressure where would you set that threshold?

    Williams
    Well personally I think that some of the research we're doing and I've got a particular interest in high blood pressure in young people, the suggestion is now that some of the damage that takes place as a consequence of high blood pressure, particularly to large arteries like the aorta, are probably irreversible and they're very subtle and cumulative over time. So maybe by the time you're 30 or 40 you've already got some damage. Now getting the blood pressure down at that stage is still hugely beneficial but the big question is what if we could detect those who are at risk much earlier, intervene much earlier with lifestyle interventions and sometimes drugs, we might be able to completely eliminate some of the detrimental effects of high blood pressure over the longer term. I think that we should be measuring blood pressure in all adults, certainly in the 20s and opportunistically whenever we get the chance in younger people. We still find young people, children, with high blood pressure too and again that's a real challenge about whether you have screening, mostly at the moment is done opportunistically.

    Porter
    Professor Bryan Williams suggesting that if you are an adult, you should know your blood pressure and get it checked more than once.

    But what about your cholesterol level? Raised cholesterol is another risk factor for an early heart attack and stroke and routinely measured in many older adults, particularly those with other risk factors such as high blood pressure and diabetes. But why wait until adulthood, why not pick up the problem much earlier by testing every child to identify the few who have very high cholesterol levels that, if not picked up and treated with cholesterol lowering statins, can lead to heart attacks in their 30s and 40s?

    Well that is exactly what doctors in America are considering following a recommendation by an expert panel that such screening should be introduced. Matt Gilman, Professor of Population Medicine at Harvard, was on the National Heart, Lung and Blood Institute guidelines panel, but didn't agree with its conclusion

    Gilman
    In a nutshell my objections to universal screening are that if we go out and measure cholesterol levels on lots of children or adolescents what we're likely to do is find a very small number who are in need of intensive treatment as say teenagers but we're also likely to identify a vast number of people who will maybe get the labelling phenomenon, which is hey you've got this issue, and start making people feel sicker than they are and some of them may even be put on medications.

    Porter
    Do we know how to manage children who have moderately raised cholesterol levels, I mean do we know, for instance, that long term treatment with statins is safe or that it's effective - how much evidence do we have?

    Gilman
    The only studies for statins in children are in those with the very high cholesterol levels. In those studies which are up to say three or four years there's good evidence that it can lower the cholesterol levels, either stop or even regress some of those early manifestations of hardening of the arteries. There's still a question about whether the adverse effects will multiply over the long term - we don't know about that. You were asking about children with more moderate elevations in cholesterol - for them there really are no studies of statin use and I think most people would feel uncomfortable even doing studies of statin use in those children with moderately elevated cholesterols. And we know that these medications can have long term side effects and we just don't know what the issue is, how much these side effects are really a problem. Let's go back to one of the major principles of screening - screening, by definition, is done on asymptomatic people. When we physicians offer a screening test it's not because the patient has come in to us and says I have a symptom, it's because we say we have a test for you that's very good. So I think that the standard for proof of a screening test should be very, very high. Hippocrates said first do no harm and I think that applies in spades to screening or early detection.

    Porter
    The other way of looking at this from a public health perspective is say look at least we'll be able to identify people who may be at higher risk of heart disease later in life and give them some lifestyle advice at an age when they might take it on board - cutting back on their weight, not taking up smoking, doing more exercise etc. - is there any evidence that it can help with that?

    Gilman
    So this is a good question too about whether knowing your number can help you actually achieve lifestyle goals better than not knowing your number. And actually there's very little evidence that this is true, especially in children and the evidence is mixed in adults. So it may be better just to say these are recommendations for everybody, that everyone should eat better, should get more exercise and in that way we're lowering the cholesterol levels of the whole population. There's really no good evidence that knowing your number or knowing your child's number helps with individual or family changes in lifestyle.

    Porter
    Here in the UK Professor Bryan Williams is keener to see similar screening introduced.

    Williams
    I think the evidence is so strong that cholesterol treatment, particularly in children with these genetic abnormalities, is so effective in almost normalising life expectancy and certainly normalising risk of heart disease, that you could justify a screening programme. The big question is always about what is the likelihood of picking it up - in other words how many people do you have to screen to actually identify one case? It's actually less than we previously thought and I think people are now beginning to think about looking at a more systematic screening of cholesterol in younger people.

    Porter
    Can you put a figure on that, I mean what sort of proportion would have a problem that would worry you?

    Williams
    One in a few hundred but you know that one case with premature disease is going to cause major problems in cost terms and not to mention the problem for the patient. So it's perfectly justifiable on health economic grounds. And I think the next wave of recommendations for screening will see a much sharper focus on identifying high cholesterol.

    Porter
    Professor Bryan Williams. Margaret McCartney, as a GP, does screening every child for raised cholesterol levels appeal to you?

    McCartney
    Well I think one of the big problems with screening is that as the professor was saying is when you're screening lots and lots of people at low risk you really have to be pretty sure that you've got a good test and then a good intervention that you can offer to people. And I think at this point in time we just don't have that quality of evidence. Having said that if someone was to come in and see me with a family history of premature heart disease or stroke, someone - a relative that's had a heart attack or a stroke at a young age - there's no doubt that that person would merit quite careful talking about testing and then testing is appropriate for all kinds of risk factors, not just cholesterol but blood pressure as well.

    Porter
    And that's the "targeted screening", in inverted commas, that we would apply at the moment?

    McCartney
    Yeah and I think it's more than that though because it's somebody actually coming in and saying look this is my story, what do we think about this and what can we do. I think that the flip side of this is that we become so focused on looking at screening or looking at medical solutions to problems when actually we should be looking at more populations based solutions to what we can do to help improve our cardiovascular numbers in the UK and we need to be talking more about sort of salts and processed foods and cycling lanes and things like that rather than looking to medicine to try and provide solutions which it really doesn't have the evidence for.

    Porter
    Margaret, thank you very much.

    But what is behind this quest to medicalise what we used to regard as normal? Well I suppose in part it's a consequence of the inexorable march of modern medicine - many of the illnesses that occupied my predecessors are no longer a threat in the developed world, so we have to look harder for foes to fight. I doubt pre-hypertension or raised cholesterol levels concern many doctors working in the poorer parts of Africa or Asia today. But there are many other factors too and I will leave the last word to Ray Moynihan.

    Moynihan
    There are in fact many drivers of this problem. The pharmaceutical industry are of course a key player here and they can't be ignored and they have a direct interest in maximising markets for their products in portraying illnesses and diseases as broadly as they can to catch as many people as they can. But you also have the professions themselves and then of course you have cultural drivers, you have this religious faith in early detection and the benefits of medical technology to save us. And I think perhaps it's these cultural issues that need more attention. And when I say culture I mean that very broadly - public attitudes, government policy, media coverage and indeed the culture within medicine itself. And the real challenge is how to wind back safely.

    ENDS

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