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Eur J Cardiothorac Surg 2006;30:819-824
© 2006 Elsevier Science NL
Editorials |
Guy's Hospital, London SE1 9RT, UK
(Email: Tom.Treasure{at}ntlworld.com; tom.treasure{at}ukgateway.net).
The tangible reward of clinical surgery is that with our own hands we change the course of disease and so improve and prolong our patients lives. That is what we find so compelling. From earliest times the goals of surgery were to staunch haemorrhage, to relieve obstruction and to drain pus. These simple tasks remain the most dramatically effective things we do. Every time we save a patient who is bleeding to death from a simple stab wound or a complex aneurysm; or when we relieve obstruction of a coronary artery, a heart valve, the oesophagus or trachea; and when we drain an empyema and see the improvement in a sick and toxic patient within hours, it is our knowledge, our skill and our craft that benefit the patient. These treatments are based on our knowledge of anatomy, physiology, pathology and the natural history of disease. We apply our knowledge in a rational and logical way; we see a direct cause and effect between what we do and the benefit we give.
In terms of evidence this can be simplified to the parachute analogyyou would be very foolish to try to fall to earth without one [1]. No trial will now be done of the parachute. Much of surgery may be viewed in that way. No trials will be done to test the fundamental principles of hip replacement, cataract surgery or valve replacement for aortic stenosis. In each case there is a clear mechanical cause for the effects of the disease and in each case they can be rectified by surgery. In these examples the effect is large and the relationship clear so no trials are needed. When the effect is small, or the cause and effect relationship is less obvious, or it is obscured by other factors, we need better evidence.
When challenged to justify what we do we have to convince those who pay. Whether it is an insurance scheme, a health maintenance organisation or a health service, we must be prepared to demonstrate that the intervention we offer is truly beneficial and cost effective or the health care resources should be used in another way. Remember that their vested interest is at least as great as ours. Health care concerns everyone. They are likely to be patients at some stage in their lives (Box 1 ) [2].
The challenge to justify what we do was spelt out by the three times Governor of Colorado, Richard Lamm [3]. It is a robust challenge. American infant mortality rates are the second worst in the developed world, in an economy that spends the highest proportion of any nation of its enormous wealth on health care. Can they justify chemotherapy in dying patients, repeated organ transplants and prolonged mechanical support, while other Americans do not have access to the basics of antenatal care? Lamm is not asking for less to be spent but better justification for how it is spent. John Yates [4] in his book Private Eye, Heart and Hip criticized British surgeons for spending too much time in private practice and neglecting the Health Service. He was not asking for more evidence but more delivery of highly effective operations. Lamm and Yates are examples of a well informed, rational and influential coterie who would control the health care purse strings.
At the same time as conventional medicine is challenged to provide evidence that what we do is effective, there is an increase in alternative and complimentary medicinea growing cult of anti-science. Take for example cupping, a therapy about two and a half thousand years old. Cups containing a little burning oil or alcohol are applied to the skin and generate suction and produce ecchymoseslike love bites! In modern America its devotees have the notion that cupping sucks out the badness of modern life. As practitioners of what is called modern medicine [5] we should remember that many accepted medical treatments will, in the future, be regarded as ineffective or actually harmful.
There are different ways surgeons obtain evidence for what we do. Controlled trials are best and the first we know of was in 1747. Of nearly 2000 sailors on a 2-year expedition around the world, more than half died of scurvy. No one knew the cause. It was two centuries later in the 1930s that the Hungarian Szent-Györgyi identified Vitamin C. But James Lind, a naval surgeon, knew that scurvy was a disease acquired at sea and that sailors recovered when they returned home. He concluded that the diet on land must contain an antidote. Lind took 12 sick men and treated them in pairs with different additions to their aboard ship diet. The two to whom he fed oranges and lemons recovered in days. Lind is given credit for the first prospective controlled trial. The British navy from then on always carried citrus fruitit was the limes that led to the British being known as limeys [6].
In the 19th century, the biggest problem blighting surgery was sepsis. The death rate from infection following compound fractures or amputation was up to 50% in London Hospitals [7]. The death rate for childhood fever reached 29% in the Vienna General Hospital in the 1840s. Nearly a third of women giving birth diedif they were admitted to the medical wards. Meanwhile on the ward run by midwives the death rate was a tenth of thatonly 3% [6]. The obstetrician Ignaz Semmelweis performed an experiment. He had the nurses and the doctors swap wardsand the tenfold higher death rate followed the doctors. Then in 1847 his pathologist Jacob Kolletschka cut his finger and died of septicaemia. Semmelweis wrote: Day and night the image of Kolletschka's illness pursued me ... as we found identical changes in his body and those of the childbed women, it can be concluded that Kolletschka died of the same disease. He saw the medical students coming directly from autopsies with soiled hands and instruments. Was it not obvious he wrote that puerperal fever is caused by conveyance to the pregnant woman of putrid particles derived from living organisms ... carried on the hands of the very people who were there to ensure the safety of their babies and of themselves? Semmelweis ordered hand washing with chlorinated water and mortality fell dramatically.
Neither James Lind nor Semmelweis had an accepted mechanism on which to base treatment. They relied on trials with control groups. These two trials were far from perfect: neither used blinding; neither had a system of unbiased allocation or randomisation that would meet present day standards; but they were good enough. The effects were large and both were controlled trials ahead of their time. A hierarchy of evidence used in development of guidelines is now familiar [8]. Systematic reviews, meta-analysis and individual Randomised controlled trials (RCTs) are best. Controlled trials as used by Lind and Semmelweiss follow and then collected case series, preferably prospective rather than retrospective (Table 1 ).
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The lowest forms of evidence are dogma and doctrine. Under this heading I place practices that cannot stand up to logical scrutiny nor have been proven in an empirical trial. Here I would include cupping, bleeding and homeopathy. We should not dismiss treatments because we do know the mechanism but these fail both the test of a scientific rationale and empirical evidence. Homeopathic medicine is based on a doctrine promulgated by Samuel Hahnemann [6,10]. He was educated in Liepzig, Vienna and Erlangen and saw doctors poisoning their patients. His theory is based on infinitely small doses of the active material achieved by sequential dilutions until there is nothing but a memory of the substance in the remaining water. At least this ensured that patients could not be poisoned. Less benign were the emetics, purgatives and the regular and copious blood letting practised by our predecessors [6]. Bleeding persisted until the 19th century, 200 years after Harvey had demonstrated the circulation of the blood. These doctors were no less rational or intelligent than us. The human intellect has not evolved over the intervening few generations. They would have offered plausible justification based on their observations and experience, and the authority of their professional status. Furthermore patients expect something to donea justification we hear today when unproven surgery is used on cancer (Table 2 ).
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On the question of changing practice, is a plausible mechanism required? While there was ready acceptance that fresh food was a good thing for sailors, there was a debate going on in the early 19th century about what caused infections. Oliver Wendell Holmes in Boston regarded puerperal sepsis as due to germs and in 1843 had suggested the link between the autopsy room and childbed fever. He advocated washing in chlorine water. He was rebutted by colleagues who insisted that puerperal fever was not contagious and certainly not caused by American doctorsperish the thought [6]. Transmission of infection was not shown until the time of Pasteur many years later (Box 2 ).
Around the same time the London surgeon Stephen Paget [12] published his book The Surgery of the Chest packed with case histories. A young man in a duel received a thrust under the pectoralis major in the third right intercostal space. A man aged 35 was admitted to Hospital with tubercular phithisis and pneumothorax on the left side. Paget's book appears to be anecdotal teaching based on individual cases. It is more than that. A young soldier in the American war was shot in the left side of the chest a little below the nipple. The American Civil War (18611865) was over when Pager was only 10 years old. He was referring to published case records of the war. So this is a case vignette, illustrative of evidence, which is more broadly based than anecdotes of his own experience. It is eclectic, based on the pooled experience of others. Understood in this way, it is akin to our weekly meetings and grand rounds. A single case is a for instance; it is not the evidence for what we teach.
James Paget is most often quoted for one of the worst predictions in the history of surgery. Surgery of the heart has probably reached the limits set by nature for all surgery: no new method, and no new discovery, can overcome the natural difficulties that attend a wound of the heart [12]. A more prescient prediction was made in the Lancet in 1898 by a physician in private practice, Dr D.W. Samways [13].
I anticipate that with the progress of cardiac surgery some of the severest cases of mitral stenosis will be relieved. This was based on his study of 70 cases of mitral stenosis in the post mortem room at Guy's [14]. Lauder Brunton [15], a physician at St Bartholomew's Hospital shared Samway's vision and eloquently set out the problem in 1902.
Mitral stenosis is not only one of the most distressing forms of cardiac disease, but in its severe forms it resists all treatment by medicine. On looking at the contracted mitral orifice in a severe case of this disease one is impressed by the hopelessness of ever finding a remedy which will enable the auricle to drive the blood in a sufficient stream through the small mitral orifice, and the wish unconsciously arises that one could divide the constriction as easily during life as one can after death [15].
Brunton was summarily dismissed by the Lancet. It was 20 years later in Boston, Massachusetts that Cutler and Levine [16] operated on mitral stenosis crudely putting a knife up through the ventricle to cut the valve. In 1925 Henry Souttar performed just the operation that Brunton had proposed, freeing the commissures. He put his index finger through the mitral valve relieving stenosis [17]. The young girl was improved and lived for several years. Surely there was a clear cause and effectrelief of stenosis improved cardiac output and reduced congestion. Cutler's first patient also survived but a further six patient died within days of surgery and he abandoned his attempts. He summarized the work in 1929 under the title a final report thus calling a moratorium on the surgery for mitral stenosis [18].
The British textbooks of medicine which came out in frequent editions throughout the 1930s noted mitral valvotomy at first in neutral tones but although there were no further recorded operations they became opposed to surgical attempts to relieve mitral stenosis. Sir Thomas Lewis in his 1943 edition of Diseases of the Heart wrote: Surgical attempts to relieve cases of mitral stenosis ... by cutting the valve have so far failed to give benefit. I think they will continue to fail, not only because the interference is too drastic, but because the attempt is based upon ... an erroneous idea ... (that) the valve is the chief source of the trouble [19]. Lewis, the doyen of clinical science, tells the surgeons that surgery is both reckless and illogical. So much for what I have credited as the logical application of basic science. The logic was flawed but the rhetoric was strong.
Two surgeons overcame this impasse. Dwight Harken a Boston trained surgeon working in an American Army Hospital in England operated to remove bullets and shrapnel in and around the heart and great vessels on 134 soldiers. There were no deaths; evidence 50 years after Paget and Samways that it was possible to work within the heart [20]. While Harken used the opportunities provided by warfare, Brock at Guy's employed some diplomacy. In 1948 he formed a club and those whose interest he needed to capture: physicians, pathologists, anaesthetists and the hospital's medical director (Fig. 3 ). On Monday 13 September 1948 Brock presented two patients with mitral stenosis to his associates. Within the week Brock's first patient was on the operating table and two more in the following week [21]. He had seven survivors in his first nine including two American patients he operated upon at Johns Hopkins, Baltimore [22]. In the USA Harken et al. [23] and Charles Bailey each had a survivor of mitral valvotomy in June 1948 and exactly 50 years after Samway's prediction mitral valvotomy was established internationally. The natural history was very well known; and it was consistently altered as shown in large case series [24,25]. The effect was large, and pace Lewis, made such good sense, that no one questions the evidence.
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There are many instances in cardiac surgery where the mechanical benefit is very evident and trials were never needed. Mitral and aortic stenosis are clear examples. There are far too many questions to subject each one to an RCT. We have to extend practice by clear reasoning in many instances. There is also a presumption by patients and their surgeons that operations must do some good. The often made statement is that randomised trials deny half the patients a chance of cure. So these surgeons presume to know that the outcome of the trial will favour their preferred treatment. There are 126 RCTs with 152 comparisons of cancer treatments in children [38]. For each trial there is a conclusion. It either favours the new experimental treatment, or it favours the existing best alternative. How many favour the new? How many favour the old? The answer it that there is an even distribution around no difference. We can draw several conclusions. One is that RCTs are inefficient because many show no differencebut no difference is a finding. With that knowledge we can choose the less unpleasant or the less expensive. Another conclusion is that the trial designers and ethics committees did their job well. Taking these 152 comparisons as a whole, the claim to equipoise was vindicated. There are many operations for which the benefit that ensues is sufficient proof but there are many things we do in cancer that might be futile. The history of cancer surgery has many examples.
If bigger and better operations were the solution to cancer, it would have been achieved by now. Survival rates in operated series appear better because of ever more refined selection through rigorous staging rather than by more heroic resections. Mesothelioma is an example. Radical surgery in the form of extrapleural pneumonectomy has been offered to selected patients by a minority of surgeons since the 1970s [39]. Results with surgery were poor so adjuvant and then trimodality therapy were instituted. Do these patients really do better than those spared the severe surgery? That is the question we seek to answer in the MARS trial [40].
RCTs are too often dismissed as too difficult in surgery. They are difficult but not impossible. For some questions there is no other way to know. When effects are small, time scales are long and there is a poor signal to noise ratio big trials are essential. The evidence for adjuvant chemotherapy after curative resection of lung cancer relies on meta-analysis of 7000 patients in 19 trials [41]. There is no target disease to treat. We have no measure of response other than long-term survival difference. There is no way that any individual surgeon can determine, on the basis of personal clinical experience, if there is more benefit than harm. The more often I practise in the top right of this graph rather than the bottom left, the more secure I feel than I am doing more good than harm.
| Box 1 So long as all the physician had to offer the patient was his own time and advice and a few herbs and powders, both medicine and society could comfortably claim that the physician's duty of fidelity was owed solely to the individual patient.
When physicians can, with the stroke of their pens, literally bankrupt the community, the community may no longer be able to tolerate that view of the physician's duty. Brody H, Miller FG. The internal morality of medicine: explication and application to managed care. J Med Philos 1998;23:384410 (ref [2] in the main list).
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| Box 2 Hilaire Beloc 1900
Cautionary Verses for Children. The Microbe is so very small You cannot make him out at all, But many sanguine people hope To see him through a microscope. His jointed tongue that lies beneath A hundred curious rows of teeth; His seven tufted tails with lots Of lovely pink and purple spots, On each of which a pattern stands, Composed of forty separate bands; His eyebrows of a tender green; All these have never yet been seen But Scientists, who ought to know, Assure us that they must be so ... Oh! let us never, never doubt What nobody is sure about!
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Footnotes
\#9734; Presented at the joint 20th Annual Meeting of the European Association for Cardio-thoracic Surgery and the 14th Annual Meeting of the European Society of Thoracic Surgeons, Stockholm, Sweden, September 1013, 2006.
1 NICE Lung Cancer Guidelines. http://www.nice.org.uk/page.aspx?o=244008. 2005. ![]()
2 Guidance on Cancer Services. Improving outcomes in colorectal cancer. NICE May 2004 Manual update. http://www.nice.org.uk/page.aspx?o=CSGCCfullguideline. 2004. NICE. ![]()
References
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T. Treasure Minimally invasive surgery for pneumothorax: the evidence, changing practice and current opinion J R Soc Med, September 1, 2007; 100(9): 419 - 422. [Abstract] [Full Text] [PDF] |
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T. Treasure and M. Utley Ten traps for the unwary in surgical series: A case study in mesothelioma reports J. Thorac. Cardiovasc. Surg., June 1, 2007; 133(6): 1414 - 1418. [Full Text] [PDF] |
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