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What's Behind The Screens?
Introduction
Not so long ago every other child had its adenoids or tonsils removed. A hysterectomy was performed on any woman who had menstrual problems and appendectomies were performed on symptom-free patients 'just to be on the safe side'. Circumcision of the sons of middle-class parents for reasons of 'hygiene' were commonplace.
These examples of ritualised brutality happened in the middle of the twentieth century: they were the medical fads of their time. You may feel that medicine has come a long way since then, but you would be wrong. Fads may change but fixations that owe more to passion than to evidence or logic are still common and still visited on a trusting populace.
The end of the century has seen the emergence of a belief that any disease can be eradicated if enough is spent on research, and if the diseases can be found before the patient knows he has them. And so the medical profession now spends a great deal of time and money looking for diseases which have no symptoms. The government reinforces the current fads with a sense of moral mission which forces submission to 'check-ups' at every routine visit to the doctor's surgery. (1) Try to say 'no thanks' and you will be branded as ungrateful or irresponsible.
Prevention is better than cure, we are told. Screening is a Good Thing - finding and treating diseases increases life-expectancy, reduces expenses in the National Health Service and promotes health doesn't it? Unfortunately, it seems it doesn't. There is no evidence that the progress of any of the diseases targeted today is influenced very much by the treatments we have for them. Finding them earlier merely increases the burden of worry. And if the government is so naïve as to believe that NHS costs will be reduced, they might reflect that the elderly cost significantly more both in their medical and social requirements and in their pensions. You don't save money by promoting longevity. The only ones to make money out of these programmes are likely to be the promoters of the private health schemes whose tests are good earners.
Many of today's dietary and medical ideas are founded on hypotheses whose logic is fallacious or flawed in some way. The basis of the diet-heart hypothesis, for example, is Keys'Seven Countries Studywhich was published in 1953. (2) Dr. Ancel Keys took data from seven countries and suggested that heart disease was high in those whose diet was high in fats, and low in those whose diet was low in fats. The first, and more obvious, flaw is that at the time there were data from twenty-eight countries that he could have used. The others did not support his argument.
What may be less obvious, however, is that, even if the data had all been presented, there is an inherent fallacy in Keys' hypothesis. That is that the one (fat) necessarily caused the other (heart disease). In this context, it is illogical to assume that because one thing exists, it necessarily causes something else to happen subsequently. For example, because night follows day, is night caused by day? (Or vice versa, perhaps?)
This paper looks at several fallacies which pervade present medical thinking.
In 1986, British General Practitioners were required to offer three-yearly health assessments to adult patients under seventy-five years of age and were encouraged to offer health promotion services to all their patients. (3) In the middle of 1991, the British government announced a green paper, entitledThe Health of the Nation, which marked a significant change of emphasis for the National Health Service. The government said that tens of thousands of premature deaths could be avoided if people could be persuaded to change their lifestyles. According to the strategy proposed by the paper, the main causes of diseases believed to be preventable would each be 'targeted' in a concerted attempt to reduce their incidence over the next two decades.
The major targets include: cutting premature deaths from coronary heart disease, claimed to be Britain's biggest killer, by 7,500 per year or thirty percent by the end of the 20th century; reducing cancer deaths, eighty-five percent of which it believes are preventable; and reducing stroke deaths by thirty percent by the end of the century. Other areas where the paper suggests that health could be improved include: obesity, diabetes, asthma, mental illness, child health, and food-borne diseases.
The fallacy that prevention is always better than cure
There is a fundamental difference between Eastern medicine and Western medicine. In the East, the emphasis tends to be directed to preventing illness from happening whilst here in the West we tend only to treat illness or disease once it is apparent. During the latter half of this century, however, there has been a shift of interest towards 'preventive' medicine in the west. On the face of it this appears to be a good thing. And, indeed there are good historical examples of where taking preventive measures has resulted in large decreases in the incidence of disease. By providing a clean, piped water supply and putting in sewers in the nineteenth century, diseases such as cholera and typhoid were eradicated from Britain. Childhood diseases such as whooping cough, scarlet fever, diphtheria and a number of deficiency diseases such as rickets were relegated to the past because children had better nutrition in the middle of the twentieth century.
To say that prevention is better than cure in all cases, however, involves a fallacy. Preventive medicine in this country today is confined almost exclusively to screening the population for signs of cancer and coronary heart disease. But this screening is not prevention of the disease, it is merely the early detection of it. For such procedures to be of use a number of criteria are well established. (4) They include firstly that the disease should be both common and serious, as screening for an uncommon disease will throw up many false results which will inevitably incur the cost of further testing, and cause unnecessary anxiety which itself is harmful; and secondly that an effective treatment for the disease is available, as there is little point in early diagnosis or detection of a disease for which there is no effective remedy.
After the screening comes the second phase of modern preventive measures. This usually involves having to change one's lifestyle in some way, and at a price which may be high. We know that a smoker is far more likely to get lung cancer than a non-smoker. The preventive measure here is to stop smoking. In this case the pleasure of smoking lost is balanced by having more money to spend on other treats. In other cases, however, there may be no compensating benefit. For example, we can avoid being hit by a bus by staying at home. But who would want to? And, although a stitch in time may save nine, if one stitch has to be inserted in one thousand people to save one individual from the nine, the economics of stitching are not so clear-cut.
We understand how infectious diseases are caused and can combat most of them. However, many modern diseases are caused not by bacteria and viruses but by the way we live or the stresses placed on us. Increasing those pressures has been shown to increase the incidences of such diseases. Unfortunately, screening for cancers, breast and cervical cancers in particular, seems to increase those stresses.
Cancer
Over the last few years the public perception of cancer has gone from one extreme to the other. Not so long ago, the diagnosis of cancer was like a death sentence; today we tend to believe that any cancer can be cured. It may appear, at first sight, that cancer is an ideal disease at which to aim a pre-emptive strike to catch it early before it spreads. But on closer examination that turns out to be a misconception. The truth is that cancers tend to remit spontaneously and then return. And while there have been advances over the past two decades in the treatment of some of the rarer cancers - childhood leukaemia, melanoma and testicular cancer, it is a sad fact that there have been no similar advances in treatments of the common cancers despite the vast amounts of resources that have been devoted to them. By telling us of the death rates we are persuaded that mass screening programmes are justifiable. In fact only if it can be shown that these death rates are falling can one say that screening for cancers is a good thing. As yet there is no sign whatsoever of any reduction in the number of deaths from the common cancers.
Breast cancer screening
The most common cancer in women is breast cancer. In Britain it kills some 13,000 women every year. (5) It might seem that discovery of it earlier would enhance the chances of a cure and, since it is more common, there would be less chance of false results.
Unfortunately, it is not as simple as that. By the time a breast cancer is large enough to be detectable by hand, it has usually been growing, on average, for some eight years. (6) Mammography may detect it at about six years. Mammography will only make an appreciable difference to the outcome, therefore, if the tumour metastasises (spreads) during the two years in between - and there is no reason to believe that it necessarily will. Women may have screening tests every three years and miss the faster growing tumours, while checking oneself will find the slower-growing ones in time for treatment. To complicate things, it would appear thatwhena tumour is found is not really important. Whether a breast tumour will kill depends more on what type of cancer it is. In many cases removal of a breast is irrelevant to the eventual outcome. It is interesting that where women have been followed for long periods, it has been found that some die with breast cancer as much as thirty years after first diagnosis of the cancer. And mortality statistics show that as yet there has been no reduction in the numbers of women dying of the disease - even with breast removal. (7)
Nevertheless, early detection of a lump and removal of a breast seems to be the most frequent course of events. Many women suffer disfigurement and much consequent psychological distress. In the USA things have taken a more disturbing turn. Doctors are actually advising women with no sign of the disease to have both breasts removed merely as a precaution. It is inevitable that far more women will suffer this mutilation than would ever contract a breast tumour for, although breast cancer is the most common cancer in women, the actual risk of any woman getting it is fairly remote.
When discussing degrees of risk, we have to distinguish between relative and absolute risk (see Table I). If one person in every hundred thousand of a population suffers an ailment, then the absolute risk is one per hundred thousand, or 0.001 percent. If the number of people suffering the disease doubles, there has been an apparently spectacular increase of 100% in the relative risk, but the absolute risk, at 0.002, or one in fifty thousand, is still very small. When the media want headlines, it is the more eye-catching relative risks that are quoted; the unspectacular absolute risks are rarely mentioned.
|
Trial |
HIP |
Two
Counties |
UK |
Malmö |
|
Reduction of relative risk of dying of breast cancer |
35% |
29% |
14% |
5% |
| Reduction in absolute risk of death from breast cancer |
0.02% |
0.008% |
0.006% |
0.001% |
A number of investigations of mammography have shown little benefit. In the trials tabled above, although relative benefits may look worthwhile, the reduction in absolute risk is, in fact, very small - in fact two of the results were so small that they did not achieve statistical significance. It may be argued that even a small chance of saving a life is worth doing, and this may be valid if the screening process enhances the likelihood of a cure. This has yet to be demonstrated.
On Wednesday 20 September 1995 Independent Television News broadcast the news that breast cancer screening was a success. To demonstrate the benefits of mammography in detecting malignancies, the article stated that doctors had saved 7,000 women's lives. This is a reduction of over half - if it were true. The real figures showed a drop of less than 1,500. By 2000, however, the number of deaths has changed little.
Adverse effects
Screening for cancer has its adverse side effects. Modern mammographic techniques are so sensitive that they can detect very small abnormalities, most of which turn out to be quite harmless. It is estimated that the value of mammography in detecting tumours is less than ten percent. This means that more than nine out of every ten of all positive results are false positives. Such over-diagnosis then leads to unnecessary breast removal 'to be on the safe side' and the trauma that accompanies such an operation. It also means that a great many unnecessary biopsies are performed. And exploratory surgery and biopsies themselves can promote tumour formation. (8) Indeed, a general anaesthetic, even without invasive surgery, is known to provide conditions which help cancers to become established. In the vast majority of cases the borderline abnormalities revealed by mammography might have been better left undisturbed.
My mother was a good example. She went into hospital in August 1994 because she was suffering from a hiatus hernia, a painful but otherwise harmless condition. While she was there, doctors gave her a full physical examination and found a lump in her breast. My mother told me that she had known about this lump, which had given no her symptoms, for over twenty years. They did a biopsy and pronounced the lump a malignant cancer. The following April, at the age of eighty-five, my mother died from a metastasis in her liver. Was it just coincidence that her breast tumour metastasised at that time?
The unnecessary physical damage, however, is only part of the problem. There is also a high degree of psychological harm. Where people have an asymptomatic cancer for which nothing can be done, finding it only gives them an unnecessary burden of distress. The high number of false positives is more serious still. Since more than ninety percent of 'positive' mammographs turn out to be false, since the number is even higher in the case of cervical smears, and since women have repeated screenings, it is inevitable that very many women will suffer unnecessary anxiety and mental stresses - which may very well potentiate the very diseases that the screening is employed to eradicate. A Canadian study suggested that women who had frequent screenings weremorelikely to die of breast cancer. (9) Even if this turns out to be untrue, the very fact that it has become an issue at all is indicative of the lack of hard evidence that mass breast screening does any good. Meanwhile, in two British studies, diagnosis of the possibility of the disease showed that it had devastating psychosexual effects on a large proportion of women. They have described being 'devastated' or 'stunned', have lost weight or begun to brood about their funeral arrangements.
False negatives can also be devastating. A 48-year old woman in California had a mammogram in August 1986. It was negative. Just three months later, in November, she found a lump in her breast. Reporting it, she was told that she had breast cancer with cancers in eleven lymph nodes. and was given only about six months to live. Fortunately, she was still with us in 1993. (10) But cases like this make one wonder how much use screening really is.
Cervical cancer screening
Cervical cancer is much rarer than breast cancer. The tests for it, therefore, inevitably incur more false positives and false negatives. Indeed, the ten percent of the female population found to have 'pre-cancerous cells' is some hundred times the number of women who will go on to develop the disease. Realistic analysis of cost-benefits shows that cervical cancer screening is so inefficient as a predictor of cancer that it is not worth doing on a mass scale.
Testing for cervical cancer is done using the Pap test, named after Dr George Papanicolaou who developed the stain used to colour the tissue being tested. In recent years, there has been a number of reports questioning the accuracy of Pap tests. In one study, at least half of all Pap tests were in error with both false positives and false negatives. Most of the errors were from poorly trained or untrained personnel misreading the slides but other errors can creep in from: collecting the samples from the wrong site, improper handling of the specimen on the slide and the use of defective dyes for staining. It has been estimated that in the USA, at least five percent of cervical Pap tests are false positives. That may not sound many, but with fifty million tests a year, this means that over two million women each year may have to undergo totally unnecessary procedures, or even surgery, for a disease they don't have. There are also false negative results that impart an unwarranted sense of safety in those who do have the disease.
Women studied in cases where a positive result has been given have shown considerable adverse psychological consequences. (11) Nearly sixty-five percent had anxieties about cervical cancer, sixty-eight percent suffered tension, over seventy percent had mood swings, fifty percent found their sexual interest was impaired and over forty percent had difficulty sleeping. Even where a negative result was given and where subjects should have been reassured that they had no cancer, many subjects had similar anxieties: over forty-three percent worrying about cervical cancer, seventy-five percent suffering tension, sixty-eight percent with mood swings, thirty-one percent with impaired sexual interest and more than a quarter having difficulty sleeping.
Two hundred and twenty-four women were screened for signs of cervical cancer in a trial at Fox Chase Cancer Centre, Temple University, Pennsylvania in 1990. Of them, 106 had normal test results which required no follow-up but 118 were recalled for a further examination. Of the sixty-five percent who turned up, not one was found to have a cancer. (12) Imagine, however, how they must have felt when they got the letter calling them back for re-examination; and imagine how worried the thirty-five percent who did not go back must be now. (13)
During the period 1988 to 1993, 225,974 women were screened for cervical cancer in the Bristol screening programme. New abnormal cells were found in 15,551 of them. Nearly 6,000 were referred for colposcopy (insertion of a fibre optic into the vagina for an optical examination). Dr A E Raffle and colleagues of Bristol point out that these numbers are excessively high in comparison with the actual numbers of cases of cervical cancer. (14) The number of women who would be expected to develop cervical cancer in a five-year period before screening began thirty years ago was in the order of 150 to 200. Even if screening has controlled the numbers of deaths which otherwise would have occurred, the authors say that that figure would not have exceeded 220. Thus during each screening round over 15,000 women are wrongly told they are at risk and 5,500 are being investigated and treated - and left with lifelong worries about cancer - for a disease which they would never have suffered anyway.
And the effect of screening is too small to detect. Despite a high take up of invitations for screening, there has been no detectable reduction in deaths from cervical cancer as a result of screening. Women who have been screened still die of the disease. Indeed over the country most of the women who die of cervical cancer have been screened.
Recently, the guidelines came under considerable criticism in the pathology literature because of the lack of scientific evidence on which they were based. (15) Even one of the guidelines' authors has been particularly outspoken on the subject. (16) Though some of these arguments may seem of academic interest, cytology departments are being forced to close or merge as a result of the guidelines, which still await scientific evaluation. Many staff feel threatened by the prescriptive way in which the guidelines have been introduced and applied and by the lack of understanding by the lay public and media of the limitations of the smear test.
There are moves to increase the numbers and frequency of screens but, as Dr Raffle,et alpoint out, until we determine why the present scheme is not having the expected benefits, we need to determine what has gone wrong before changes are made.
Cervical cancer is a violent and fast-acting cancer. Testing for it every three years inevitably means that most cancers will be missed. Professor James McCormick of Dublin University Medical School concluded in 1989 that this screening 'is an expensive contribution to ill health because the harm exceeds the possible benefits by a substantial margin'.
Many General Practitioners would agree with that. But if they do not comply with guidelines set for them by government, that they get eighty percent of their female patients screened, they are liable to suffer financial penalties. General practitioners in Britain are paid to do cancer tests. Such financial considerations are a powerful incentive to comply with the guidelines, even if you don't believe they are effective.
Prostate cancer
You may have noticed that where cancer screening in Britain is concerned, it seems to be confined to women's cancers only. One in two men will suffer cancer of the prostate and to screen for the disease would be very easy and cheap; but it isn't done. Why not? Probably because population screening is not medically but politically motivated. (17) Women are becoming more active and more influential. It is designed to make the electorate, and particularly women, believe that the government cares for them.
Some years ago in the USA, it was fashionable to screen men for prostate cancer although no trials into possible benefits had been done. It was politically correct to give men the same benefits as women. Recently, however, doubts are being voiced. Prostate cancer is a quiescent cancer which is very common in elderly men. But since the operation is more radical than simply the removal of the prostate and often leaves the patient incontinent, it is unjustified in men who feel all right as they are.
In 1995 Dr Thomas Stuttaford used his column inThe Timesto advocate a battery of annual screening tests - from liver function tests to abdominal ultrasound scans - and suggested that these tests would 'set your mind at rest', completely ignoring the mental distress that screening tests can cause. One of the tests he proposed was a blood test for prostatic specific antigen (PSA), which is often raised in prostate cancer.
Although he had no symptoms, Dr Stuttaford followed his own advice, found his PSA was high, and had surgery. On 9 December 1997, as part of a Christmas appeal for research into prostate cancer, he described his ordeal with 'A hidden killer that can strike without warning'. He suggested that while radical prostate surgery is a routine procedure in the United States, where screening for prostate cancer is available for people aged over fifty, this operation is less common in Britain, and cited cost as the reason. He was concerned that if demand for radical prostate surgery increased in Britain, surgeons 'may lack the necessary technique' and 'anaesthetists may not have the temperament or experience' to cope with the workload.
Medical opinion in Britain, however, is against universal screening for prostate cancer and Professor Stephen Woolf from Fairfax in the United States, thinks we are wise. Writing in theBritish Medical Journalin 1997 (18) he pointed out that in the USA 'the introduction of uncontrolled prostate specific antigen screening spawned a prostate cancer "epidemic"'. He concluded that 'Until compelling evidence becomes available, healthcare systems have good reason to defer prostate screening in lieu of other priorities'. Professor Woolf highlighted a systematic review commissioned by the NHS Health Technology Assessment programme, which added to the evidence against routine screening for prostate cancer.
Peter Whelan, a consultant urologist, highlighted the fact that so far there 'has been only one paper of a prospective randomised trial comparing radical surgery with observation, and no difference in survival in this much criticised paper was shown'. He argues that prostate cancer screening would promote stress and anxiety. (19) And the American Cancer Society guidelines published in their journal,Cancer, while proposing screening in people aged over fifty, also point out that 'There has been no direct evidence to show that PSA screening decreases prostate cancer mortality rates'. (20)
In response to Dr Stuttaford's article, Dr Muir Gray, joint programme director of the national screening committee, wrote toThe Timesexpressing his dismay at the way in which Dr Stuttaford was misleading his readership. Dr Muir Gray emphasised that screening for prostate cancer was not rejected on financial grounds and stressed: "the scientific evidence is that screening for prostatic cancer does not reduce mortality and does cause harm by exposing people to a procedure with the side effects of incontinence and impotence where there is no evidence that they will benefit" The Times did not publish Dr Muir Gray's letter, but passed it on to Dr Stuttaford. On 13 January 1998 Dr Muir Gray wrote again to The Times: "Dr Stuttaford is, of course, entitled to give a personal opinion but we assumed that the same standards of evidence applied to your medical page as to your other pages, for example that journalists should check their sources and that editors should ensure that they have done so".
By 29 January, neither of Dr Muir Gray's letters had been published inThe Times, but Dr Stuttaford used his regular column to persuade his readership: "Why early prostate tests are essential". In building his argument, Dr Stuttaford discussed evidence published in theJournal of the American Medical Association and Cancer. Furthermore, Dr Muir Gray's unpublished letters were selectively used to develop the point that screening for prostate cancer should be available in Britain. While stating that Dr Muir Gray had written in to criticise his opinions, Dr Stuttaford failed to explain that Dr Muir Gray's argument is that the weight of evidence is against prostate cancer screening. "Dr J. A. Muir Gray," he told his readers, "has written in to the Editor ofThe Timesto complain of my support for screening patients for prostatic cancer when they have no symptoms". He conveniently omitted to mention that Dr Muir Gray had hoped to offer the readers a chance to view the evidence for themselves when he wrote to The Times, "If Dr Stuttaford has the evidence, let him produce it for a face-to-face debate; for those who would like to see the systematic review of the evidence on which policy was made they can look at the summary on the web page: http://www soton.ac.uk/-hta/summ 102.htm."
Dr Stuttaford feels that the decision not to print Dr Muir Gray's letters was an editorial one, and probably because of a shortage of space. But he adds, "I wouldn't have published them either; they personalised the problem, and didn't take the argument further forward." He argued that the campaign for prostate cancer screening is justified. The Times, he suggests, has been right in the past about breast cancer and cervical cancer screening: "I can't think of when the Times has been wrong and the NHS has been right... . You don't expect to see a reduction in mortality straight away, because you're going to uncover the undiagnosed pool of prostate cancer." Moreover, he maintains that his use of Dr Muir Gray's unpublished letters in the more recent article about prostate cancer screening was acceptable, especially as he believes he put Dr Muir Gray's points across fully and fairly. The fullest and fairest way would surely have been to publish Dr Muir Gray's letters.
Medical columnists for newspapers reach a wide and vulnerable audience. As such, their advice should be well researched and balanced. The Times and Dr Stuttaford have a responsibility to redress the imbalance over prostate cancer screening, which has been heightened by their use of Dr Muir Gray's letters.
Coronary heart disease screening
It is said that coronary heart disease is our biggest killer, so here it is fondly hoped that screening can be of the greatest benefit. But even today, we do not know what causes coronary heart disease and, without knowing its cause, cannot know how to cure or prevent it. As there is no point whatsoever in detecting a disease for which there is no known effective treatment, screening for it is a total waste of time and resources.
But some will say that we do know the cause of coronary heart disease; it is high cholesterol, or too much fat in our diets, or not enough exercise, or . . . In 1981, two hundred and forty six 'risk factors' for heart disease were listed. (21) It's now well over three hundred. What this list tells us is that we really have little idea what causes coronary heart disease. What is certain is that if they all do play a part, we have no chance of defeating the disease.
In an attempt to help those at risk of heart disease, blood cholesterol is usually the risk factor that most of the intervention is designed to change. But before an attempt can be made to modify it, individuals with high levels have to be identified. In Britain, general practitioners, practice nurses and health visitors are starting to use desk-top cholesterol testing machines, the majority of which have been loaned by drug companies. A suggestion in theLancetis that this is designed to enhance the drug companies' profits by increasing sales of cholesterol-lowering drugs and questions their ethics. (22) There is also the question of the psychological harm that could be done to people in view of the United States experience of the inaccuracy of such machines.
The first problem lies in deciding what to test for. As a predictor of coronary risk, total blood cholesterol turns out to be irrelevant, (23) and merely testing for that is regarded by many experts as misguided. Far more reliable, they claim, is measurement of HDL (the 'good' cholesterol). However, in tests of the accuracy of checking for HDL at various laboratories, (24) values differed by as much as forty percent in ninety-five percent of the samples tested. In another study, (25), sixteen instruments manufactured by nine companies were tested in forty-four laboratories. In this test, although the inaccuracies of the machines were lower at 3.6 to 4.4 percent, biases attributed to the methods used ranged from -6.8 percent to +25 percent The accuracy of desktop machines is even more suspect. A third study to evaluate the ability of cholesterol screening to detect individuals with blood cholesterol abnormalities concluded that 41% of those with abnormal levels would not be detected using present guidelines. (26)
To compound the machines' errors, an individual's blood cholesterol level changes constantly. There is a gradual increase in the general level throughout life quite naturally. But it also changes from day to day and even from minute to minute quite naturally. If the patient ran to the surgery it would be higher than if he walked. If it is tested sitting down, it will be higher than if he is lying. If he is anxious about the result, that can elevate the result. Imagine that you are asleep in bed at 2.00 am, and you are woken suddenly by what you are certain is a burglar. You will know how quickly your heart starts to race - well that is how quickly your blood cholesterol level will rise - and for the same reason. Raised blood cholesterol is part of the 'fight-or-flight' reflex. If you are rested and relaxed your blood cholesterol level will be lower than if you are tense. The difference can be as much as twenty-three percent. (27) For any sort of accuracy, a person's blood cholesterol level needs to be checked at least hourly over a whole day or daily for a month. I wonder how often that is done.
If you add the variations in your actual blood cholesterol level when the test is done to the inaccuracy of the testing equipment, the results can be so far divorced from reality as to be totally worthless.
The hustlers move in
Towards the end of the century even more worrying trends have appeared as commercial firms seize the opportunity to make a profit from the public's confusion and lack of knowledge. One example is the sale of home cholesterol testing kits such as those from the shops of Boot's the chemist. These tests will be self-administered - that inevitably means by the unqualified and inexperienced. Even in medical hands, these are likely to give even more inaccurate results than the desktop machines and, since most people will have little idea of what the figures really signify, these figures are likely to cause even more unnecessary anxiety without any chance of benefit. Another worrying trend is the advent of 'health awareness companies' such as Health Beat Ltd of Liverpool. This firm deploys impressive official-looking caravans in towns around the country and offers to test people's cholesterol and blood pressure for a fee of £10. I visited one (I did not have any tests) and talked to the 'doctor' in the white coat who was staffing it. Using a portable machine, his job was to test people and, based on the result, give them a prognosis and medical advice. Even if the readings he got were 'unhealthily' high, he did not advise people to go their own doctors for confirmation. After I had spoken to him for a short time, it became obvious that he knew very little about his job. On being asked, he admitted that he was not medically qualified and did not have even a rudimentary knowledge of the body's functions. The whole charade was a dangerous confidence trick: someone, dressed to look like a doctor, doing tests and giving unqualified advice for a price - when your own general practitioner will give you a better service for nothing.
The evidence of fallacy
The proponents of screening for heart disease risks want us to modify our lifestyles to avoid or minimise those 'risk factors'. But there is already a considerable body of evidence from expensive long-term trials that such a programme does not work. In the five major intervention trials, several of the more 'important' risk factors, such as smoking, diet, blood pressure and cholesterol, obesity, and lack of exercise were altered. They totalled a massive 828,000 man-years of study and came up with the following results:
- deaths due to coronary heart disease in the intervention groups totalled 1,015, and in the control groups, 1,049;
- the number of deaths from all causes was 2,909 in the intervention groups against 2,947 in the controls. That, at less than one death in 2,500 men per year, is well within the limits of chance.
In three trials where blood cholesterol had been the target, 115,176 man-years of observation showed a reduction of eight deaths from heart disease in the intervention group over the controls, but thirty-five more deaths in total, thus tending to confirm yet again that lowering blood cholesterol may do more harm than good.
Real confirmation came in an analysis of thirty-five randomised clinical trials, published in 1993. The paper's authors conclude that 'population screening . . . whether in the high street or the general practitioner's surgery is not currently indicated. Such screening may, indeed, result in large numbers of people being treated for whom there are no benefits, or even net adverse effects.' They conclude that 'Population cholesterol screening could waste resources and even result in net harm in substantial groups of patients'. (28)
That prevention is always better than cure is a fallacy in itself, but in the modern concepts of prevention and screening, that fallacy is compounded as it is based on a number of other fallacies.
The fallacy of cheating death
What we hear from those who would have us change our lifestyles is that, if we change, thousands of lives will be saved. This involves the fallacy of cheating death. We are not an immortal species, but have a biological lifespan which is probably about eighty-five years. Some of us are programmed genetically to die earlier and others destined to get a telegram from the Queen. Not one of us would last for ever even if all cancers and heart disease were eradicated.
As life expectancy is approaching biological lifespan in the Western world, very little is likely to be achieved in terms of increases in life-expectancy. The average age of death from cancers in Sweden is 74 for men and 75 for women. Average ages of death from all other causes are 76 for men and over 80 for women. The numbers of deaths from coronary heart disease are falling. The mean ages at death from coronary heart disease are 76 for men and 82 for women. In these circumstances, even the gains which might be achieved by such unrealistic goals as the total elimination of CHD must be relatively small. It has been calculated that if there were no cancer deaths before the age of 65, which is a pipe dream, mean life-expectancy would be increased by only 7 months.
Conclusion
All that the interventions have achieved is to transfer the cause of death from one category to another, an achievement which has no importance unless, perhaps, it is accompanied by the prolongation of useful and happy life.
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