Select Committee on Economic Affairs Minutes of Evidence


Examination of Witness (Questions 400-419)

Professor Sir Richard Peto

14 FEBRUARY 2006

  Q400  Lord Skidelsky: It is paragraph 9, page 2. You have the sentence: "For example, if investigators were unable to achieve statistical significance at the standard 95 per cent confidence level to confirm their a priori hypotheses, they merely lowered the confidence level to 90 per cent." Is it the case that by lowering the confidence level you increase the probability of accepting the wrong hypothesis as correct? If that is so, then one may be sceptical about the science.

  Professor Sir Richard Peto: I think this is a caricature of what has actually gone on. Yes, certainly, as you know, you are going to get people who are enthusiastic about tobacco control wanting to have studies demonstrating the hazards of passive smoking and, as a result, you will get some claims that are not justified. It is when you look at the totality of the evidence and try to get all of the evidence together, and try to assess the extent to which selective publication of positive results could cause problems, then I think you do get a consistent picture that there is some excess risk of lung cancer among those who are exposed to passive smoking, from other people's smoke, on a regular long term basis. The comment by the tobacco manufacturers is okay as a comment on some particular studies, but it is not okay as a comment on the totality of the evidence. When you start putting the data from several dozen studies together, the fact that one or other of them individually claims significance or not is just point-scoring, and that is what this is, it is just point-scoring.

  Q401  Lord Skidelsky: Could I draw you out on one further thing. You have been unwilling to quantify the risks from passive smoking.

  Professor Sir Richard Peto: Yes.

  Q402  Lord Skidelsky: You say there is an increase in risk but you do not know how much it is.

  Professor Sir Richard Peto: Tobacco smoke is far and away the most important cause of human cancer in the world, and chronic exposure to it, even at low levels, is going to produce some increase in the risk of developing cancer, not only among lifelong non-smokers but also, more importantly, among ex-smokers, who are well off the zero on a dose-response curve.

  Q403  Lord Skidelsky: You may not want to give your opinion on legislation, but would you say that the risk justified the legislation which is now being proposed, or some legislation that may be more proportionate to the risks?

  Professor Sir Richard Peto: I am sorry, I am not trying to be evasive, but when we document the extent to which smokers kill themselves, I do not try to say what laws should or should not be made about what smokers themselves do. I think trying to get evidence as to what hazards are is not the same as proposing legislation.

  Q404  Lord Skidelsky: But legislation should be based on some measure of hazards. That is the basis of all—

  Professor Sir Richard Peto: We know this is the most serious of all human carcinogens. In terms of numbers of deaths, just lung cancer alone is causing about one million deaths a year worldwide and smoking kills a lot more people by other diseases than by lung cancer. This is the most serious of all human carcinogens. It has to be causing some risk. Whatever risk it is causing, there is going to be uncertainty about it. It is difficult to measure small risks reliably, particularly on heart disease and particularly in people who are ex-smokers and have some substantial exposure previously. But, environmental tobacco smoke has to be causing some risk. In this country alone, we are talking about 100,000 deaths a year from smoking—actually, it used to be more than 100,000. These are really big numbers. Trying to minimise exposure or to limit exposure to such agents seems attractive to many people. The fact that it is difficult to measure these low risks is always going to be the case. Whatever those risks are, it is going to be difficult to measure them.

  Q405  Lord Vallance of Tummel: Sir Richard, I wonder if I may change the subject a little bit because you have already answered the question I was going to ask on smoking en passant. Could we move on to hospital acquired infections.

  Professor Sir Richard Peto: I have been fairly useless on the previous questions and I am probably going to be even more useless on this.

  Lord Vallance of Tummel: That is fine. Do not think that because you are being useless it is not helpful.

  Chairman: You may take some comfort from the fact that with some people who are very assertive about what they believe we are not very convinced they are right either. We think you are more likely to be right if you are somebody who shows a little doubt about something.

  Q406  Lord Vallance of Tummel: If you shed doubt on an area where there is apparent clarity before, that may be very useful indeed. Media reports have highlighted the risks of contracting MRSA.

  Professor Sir Richard Peto: Yes.

  Q407  Lord Vallance of Tummel: Do you have an assessment of the scale of this problem in the UK versus, say, other European countries? Do you think the media reports are accurately conveying the scale of the problem or are they exaggerating it?

  Professor Sir Richard Peto: I am sorry, I can only make an uninformed comment. I suspect that there is a considerable exaggeration. And, very often, when things are actually going quite well in this country in terms of medical benefits, it gets represented otherwise. We have the best decrease in the world in lung cancer mortality, and we have the best decrease in the world in breast cancer mortality, but these do not get emphasised. You are always told how bad things are. In some respects we do very well but this does not come across. There is a tendency, it seems to me, to seek fault in the hospital system. The hazards of infections acquired in hospital causing the death of patients who otherwise would have had some chance of a reasonable life, it seems to me, have probably been exaggerated. My impression on reading about them is that they probably have been, but that really is not a serious scientific comment.

  Q408  Lord Vallance of Tummel: Are you aware of any international comparisons between the UK and other countries?

  Professor Sir Richard Peto: Not serious ones, but that does not mean that there have not been any. I am sorry, I just cannot help you.

  Q409  Lord Vallance of Tummel: This could be helpful. You are really saying—

  Professor Sir Richard Peto: I am talking about my ignorance. I am not saying it is not known. I am saying that I do not know it.

  Q410  Lord Roper: The same problem may arise on this question, as this is one, more generally, on methodology. A report by the National Audit Office, Improving Patient Care by Reducing the Risk of Hospital Acquired Infection published in 2002, suggested "there has been limited progress in improving information on the extent and costs of hospital acquired infections" and that "progress in preventing and reducing the number of infections acquired while in hospital . . . continues to be constrained by lack of data". Looking at this more generally, could you give us your views about the quality of data collection and statistical analysis provided within the National Health Service? Does current statistical practice within the NHS adequately support health care risk assessments and cost-benefit analysis? If not, do you have any suggestions as to what could be done to improve the situation?

  Professor Sir Richard Peto: Are all the statistics gathered that could possibly be useful? I am speaking now as a professor of medical statistics, and if you send everybody who is supposed to be treating patients and running around wards chasing statistics—more and more and more statistics—you may not be doing patients a favour. There are things which are worth recording and there are some things which are not. There is one thing that can be done to reduce hospital acquired infections however, and that is at the time of surgery. There are cases where surgeons definitely choose not to use prophylactic antibiotics (just antibiotics in case the patient gets an infection) because they are afraid of encouraging the emergence of resistant strains. But I think that one could reduce peri-operative infection rates by the use of prophylactic antibiotics. Experts do disagree as to whether this is an appropriate strategy. My view, however, is that at least we know that prophylactic antibiotics can help protect the individual undergoing surgery, and the future hazards are somewhat theoretical, although there are some clear examples of antibiotic resistance emerging.

  Q411  Lord Roper: Would it be worthwhile for us to invest more in statistical analysis and data collection?

  Professor Sir Richard Peto: I think you have to be very particular as to what it is you are going to do. If you lay down blanket rules about needing more and more and more information about this and that, and people have to run around completing tables and filling in forms, then this may not be helpful to effective patient care. There are times when things go wrong and they need to be recognised, and there are times when the collection of routine statistics helps with this. But you have to be quite careful when you try to insist on the collection of additional statistics. I would like to make one point about statistics in this country, if I may. Over the last half century, until the last few years, we have had a tradition of medical statistics being fairly freely available to bona fide medical researchers to help them do studies and to understand the causes of diseases. Concerns, mostly within the last ten years, over personal privacy have now produced a situation where really serious studies cannot be done; where they are so impeded by data protection regulation which really is not of benefit to anybody, that serious damage is caused to medical research that could save lives. I think it would be very useful if there were to be a serious reduction in the extent of the control of the use of personal data for medical research by bona fide medical researchers. We have reached a situation where great damage is done to serious research. It is, of course, very difficult to point to specific examples of where research would have been done but was not, because you do not know what would have been discovered, but we can look at some things that were discovered in the past and realise that they would not be able to be discovered now. For example, the hazards of German measles in pregnant women were discovered, among other things, by an inquiry where they took the records of women who had applied for sick leave for measles or whooping cough or German measles and who then applied for maternity support later on, and then went back and tried to interview them to find out which of the children had any disabilities and to relate that to the illness that the mother had suffered. This inquiry confirmed that it was specifically German measles, not ordinary measles and not chicken pox, which was producing blindness and brain damage, and, as a result, pregnant women were protected. You could not do that now: it would be using records for purposes for which they were not obtained. And, the question is just: why not?

  Q412  Chairman: This strikes me as being important.

  Professor Sir Richard Peto: This is something which would be a really important area for concern.

  Chairman: The law about unintended consequences of increased privacy produces this problem. Has there been anything published on that? Is there any documentation or article we could read? It is really quite interesting.

  Q413  Lord Roper: It has come up in recent legislation, I think. We did debate it in the House.

  Professor Sir Richard Peto: Yes.

  Q414  Lord Roper: If Professor Peto has some other sources, that would be very helpful.

  Professor Sir Richard Peto: Perhaps I could answer that in writing subsequently or I could refer to the article written by the late Professor Sir Richard Doll in 2001 in the British Medical Journal on the subject. It was a brief article and he argued very strongly that, for moral reasons, the amount of restriction on the collection of medical statistics has now reached a situation which he described as immoral. He was talking as somebody who had discovered quite a lot of things from the collection and appropriate use of routine statistical information.

  Chairman: All right. We have one or two more questions, and we should get on.

  Q415  Lord Sheldon: In talking about distortion by the media of medical risks, there is the example, of course, of the MMR vaccine.

  Professor Sir Richard Peto: Yes.

  Q416  Lord Sheldon: How are we going to get a balanced picture of the risks involved here?

  Professor Sir Richard Peto: So far there seems to be no evidence of any risks involved, and yet that has not stopped it being a major scare. That is an extraordinary example because there is no good evidence of any such risks, yet it just runs and runs.

  Q417  Lord Sheldon: Should the health care professionals not get involved with this with the media?

  Professor Sir Richard Peto: Yes, but then the media will try to get a "balanced" view by finding somebody who says it might be dangerous. This is one of the prices of having a free press, that they print whatever rubbish they like in circumstances like this. In this case, to be fair to the media, there was an eminent professor making the claim, so they are bound to report it, but it is an absurd story. It is an absurd episode, taken as a whole. I do not really blame the media for it, it is just one of these things that happens, and more such things will happen again and again.

  Q418  Lord Macdonald of Tradeston: As a supplementary to that, if we take the role played by politicians—which can sometimes seem political or innumerate or cynical—they perhaps have a greater duty of responsibility than the press. Is there a way in which medical professionals could try to add more weight and evidence to the kind of debates that are held in Parliament and to influence the politicians perhaps to be better informed and more responsible?

  Professor Sir Richard Peto: I do not know of any obvious steps, I am sorry. My main concern, still, is with the extent to which people are getting killed by tobacco in this country. I am sorry to come back to it, but it is such an absurd situation, where you have 100,000 deaths a year in this country alone. However, this country has done a lot better than many other countries. Indeed, we have a very nice control group just across the Channel in France, where the French delayed about 20 or 30 years longer than we did before trying to take tobacco seriously. The result was a really marked contrast in lung cancer trends between France and Britain.

  Q419  Chairman: I wonder if I could press you on a bit with another side to our interest: How serious is the threat to antibiotic resistance?

  Professor Sir Richard Peto: Certainly there are bacteria that are difficult to treat and in some cases this has been produced by widespread use of antibiotics, but, overall, there is the most extraordinary decrease in mortality from infections. My colleague Dr Gary Whitlock has recently produced a graph describing the patterns of mortality in Britian, running back to 1838, when statistics first began to be collected. Because of public health measures between 1850 and 1950 the death rates kept on dropping and dropping until the middle of the 20th century, at which point effective drugs came in, since when the residual risks of death from infection have kept on dropping. For example, the probability of a five year old dying before age 15 is now only about one-third what it was 150 years ago when some of the portraits in this committee room were painted. In looking at what is wrong, it is really worth remembering what we are getting right. We have had the most extraordinary reductions in the probabilities of death in infancy, death in childhood, death in early adult life and death in middle age in this country. There have been extraordinary changes over the last 100 years, and largely favourable. So when we do talk about the use of antibiotics and the encouragement of antibiotic resistance, remember that many people—I, for one—have had their lives saved by antibiotics. That is the main thing. They do work, but they do not work if they are not used. The damage that they do is a small fraction of the good that they do.


 
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