DOES modern medicine do more good than harm? Not as often as it could and should, say a growing band of doctors and scientists devoted to the cause of 鈥渆vidence-based medicine鈥. 鈥淚t鈥檚 a phrase that lots of doctors hadn鈥檛 heard a year ago, and many still haven鈥檛,鈥 says Richard Smith, editor of the British Medical Journal. 鈥淏ut in no time at all, everyone will know the phrase. Evidence-based medicine is the future.鈥
This radical movement wants doctors to use treatments that have been shown to work in valid trials. 鈥淚t鈥檚 an incredibly simple idea,鈥 says Iain Chalmers, director of the UK Cochrane Centre in Oxford, 鈥渁nd one that is blindingly obvious to most lay people.鈥 Given the scientific aura of modern high-technology medicine, he says, 鈥渕ost people find it mind-blowing that it hasn鈥檛 been done already鈥. Yet it is only now that healthcare specialists from a wide range of disciplines have set up an international attempt to 鈥渁ssess the existing evidence and concentrate on the reliable stuff鈥, says Chalmers.
It looks as though 1995 will be the year when this rational approach at last comes of age. The Centre for Evidence-Based Medicine recently opened in Oxford, under the directorship of David Sackett. Sackett will also coedit the Journal of Evidence-Based Medicine, which will be launched by the BMJ鈥檚 publishing empire in September to coincide with a landmark conference on science-based healthcare. A third key event will take place this spring, with the launch of the Cochrane Database of Systematic Reviews. This will focus on a number of diseases, drawing conclusions about which treatments work and which do not from all the available randomised controlled trials.
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These RCTs, in which patients are randomly assigned to receive either the treatment being tested or another, are critical to all three ventures. Only these studies, says Sackett, can remove the biases that inevitably confound doctors whose clinical judgment is based largely on the day-to-day experience of treating a variety of patients.
Sackett, who gave up a high-profile post at the medical school of McMaster University in Hamilton, Ontario, to take up the Oxford job, has spent years establishing the need for a shake-up in the way doctors learn and practise medicine. 鈥淐linicians begin to deteriorate as soon as they leave their training programmes,鈥 he says. 鈥淚t is not just current knowledge that deteriorates 鈥 performance deteriorates. For example, we have shown that whether or not you get your high blood pressure treated has more to do with the doctor鈥檚 year of graduation from medical school than with your degree of organ damage.鈥
Cases in which RCTs have exposed misinformed practice are legion. A survey of randomised trials in pregnancy and childbirth about to be published* found that out of a hundred procedures commonly carried out by obstetricians and midwives, about twenty are actually harmful. For example, after childbirth, some women who have episiotomies suffer pain during sexual intercourse. An RCT found that women whose stitches are of one type of catgut are much more likely to experience this pain 鈥 even up to three years later.
Sackett also cites an example from the late 1970s, when American cardiologists gave drugs such as encainide and flecainide, which suppress extra, irregular heartbeats, to heart attack patients who showed signs of these unstable rhythms. When the results of an RCT were published in 1991, doctors realised the drugs made patients more likely to die rather than less.
Textbooks, review articles and colleagues 鈥 the major sources of information for most doctors 鈥 quickly become out of date. 鈥淚 think every doctor realises that they are out of date,鈥 says Sackett. 鈥淭hose that don鈥檛 are really deluding themselves.鈥 The question is how to encourage doctors to find out about, and then act upon, the best available evidence.
Wasting time
Some doctors do not even bother trying to keep up with the latest research. But even those that do may be fighting a losing battle. One problem is the sheer volume of new information that bombards them 鈥 four million articles are added to the biomedical literature each year, many in foreign languages. Also, many doctors do not know how to recognise which papers give reliable results, and which can be ignored. Sackett cites a simple rule of thumb: 鈥淚f you鈥檙e scanning an article about therapy and it is not a randomised trial, why on earth are you wasting your time?鈥
Scouring the general medicine journals for articles that were methodologically valid and clinically relevant, Sackett鈥檚 team found that 鈥渙nly about 10 articles per month were worth reading, against a background of between 250 and 300 articles鈥.
Sackett is eager to 鈥渉elp folks learn how to learn鈥. He has co-written a book, Clinical Epidemiology, now in its second edition, that is intended to help clinicians learn how to track down evidence, appraise it, and apply it in their clinical work. But if doctors do not have the time or inclination to do the critical analysis themselves, he says, they can turn to a new breed of publications that has 鈥渧alidity filters鈥 built in, such as the Journal of Evidence-Based Medicine.
Three years ago, Brian Haynes of McMaster University set up a similar journal for American doctors specialising in internal medicine called the ACP Journal Club. It has been a runaway success, and surveys suggest it is read by a higher percentage of its subscribers than any other journal. The journal gives one-page summaries of articles that are methodologically valid and clinically useful, and which have already been published in conventional journals. Each summary is backed up by a commentary that highlights the study鈥檚 failings and strong points. The new journal from the BMJ stable will have a similar format, but will cover more areas of medicine from an international perspective.
The Cochrane Database of Systematic Reviews will be an even more rigorous publication that doctors read for the latest, most reliable evidence. Individual RCTs based on small numbers of patients can be inadequate for drawing conclusions about the benefits and side effects of some treatments. So recommendations in the database will be based on systematic reviews: critical overviews of all RCTs conducted anywhere in the world on particular treatments. These will be updated regularly in the light of new evidence and critical feedback from doctors.
The first issue 鈥 to be published on computer discs and CD-ROM, and on the Internet 鈥 will contain between twenty and thirty reviews dealing with the treatment of stroke, schizophrenia, parasitic diseases and problems in pregnancy and childbirth. The idea is that doctors will be able to call up the relevant review and use it to help them decide how to treat their patients. Already, says Chalmers, there is an obstetrician in Montreal who takes his laptop computer on ward rounds and discusses the latest evidence from the database with his patients.
The reviews are the fruit of the Cochrane Collaboration, a network of more than a thousand people around the world, including scientists, doctors, epidemiologists and consumer representatives. They have agreed to collect and analyse data from trials according to rigorous standards, and to work on updates for the rest of their careers. All this attracts little kudos and no control over copyright. 鈥淚t is not for the faint of heart,鈥 says Sackett.
The network is coordinated from a network of eight national centres. Chalmers鈥檚 centre in Oxford is Britain鈥檚 contribution. It opened in November 1992 and is funded mainly by the research and development arm of the NHS.
There is much still to be done, and even the first step 鈥 tracking down all the RCTs of a particular treatment area 鈥 is proving difficult. Computerised medical databases, such as Medline in the US, have turned out to be of limited help. 鈥淥ut of 100 000 Medline records we surveyed,鈥 says Chalmers, 鈥渨e found 20 000 that should have been coded as RCTs and hadn鈥檛 been.鈥
Then there is the 鈥淭ower of Babel bias鈥. Researchers in non-English speaking countries tend to publish their most spectacular results in English. Studies that shed doubt on the value of a treatment are often written up in other languages, or are not published at all. 鈥淥n the treatment of stroke, for instance, probably as much as 40 per cent of the relevant evidence has been published in Japanese,鈥 says Chalmers.
The Cochrane Collaboration gets its name from the late Archie Cochrane who, as director of the Medical Research Council鈥檚 Epidemiology Unit, then based in Cardiff, was one of the first to study the occupational origins of lung disease in Welsh coal miners. Cochrane worked on one of the first RCTs, which explored the effects of taking aspirin after a heart attack, and he drew attention to the medical profession鈥檚 astounding ignorance of which treatments work.
Challenging the dinosaurs
In 1979, in an essay, Cochrane criticised the profession for not having organised systematic reviews of RCTs. 鈥淭he criticism was totally justified,鈥 says Chalmers, 鈥渂ut now we are getting on with the job.鈥
鈥淭he most important development in healthcare in the past half century is the randomised controlled trial,鈥 Sackett asserts. 鈥淎nd the most important development in medicine in the next twenty years will be the systematic review of RCTs in healthcare 鈥 the Cochrane Collaboration.鈥 However, persuading doctors to use this information remains a challenge. 鈥淎 number of randomised trials have shown that simply providing people with information doesn鈥檛 change behaviour,鈥 says Sackett. 鈥淵ou need behavioural strategies to change behaviour.鈥 The best way forward is to give individuals feedback on their performance, visit doctors where they practise to point out better ways of doing things, and send doctors to places where the proper care is carried out.
But will doctors resist the movement towards evidence-based medicine, seeing it as a threat to their autonomy and clinical authority? 鈥淚 hope doctors will see it as something helpful, not as something that is used against them,鈥 says Smith. But he acknowledges that evidence-based medicine has acquired a 鈥渟lightly nasty flavour鈥 in the US, where insurance companies have taken an inordinate interest in it. Doctors there fear that insurance companies will try to restrict clinical freedom.
Sackett argues that evidence-based medicine could actually increase physicians鈥 authority. 鈥淧ower comes from knowledge, and they will know more and be more up-to-date.鈥 He admits that there are still 鈥渄inosaurs鈥 among clinicians, 鈥渨ho have been getting away with simply yelling louder, frowning sternly and putting down their juniors鈥. But he is confident that their days are numbered. Not only are younger doctors going to be better informed than they are, says Sackett, but so are the patients: 鈥淭hrough things like the Cochrane Collaboration, consumers are going to know what works and what doesn鈥檛.鈥