Paul Glasziou: Six proposals for evidence based medicine’s future

This blog is part of a series of blogs linked with BMJ Clinical Evidence, a database of systematic overviews of the best available evidence on the effectiveness of commonly used interventions.

Gordon Guyatt coined the term “Evidence based medicine” (EBM) over 20 years ago, and it has had a remarkable global influence. But EBM is not a static set of concepts, set in stone tablets in the 1990s; it is a young and evolving discipline. The fundamental concept of EBM—using the best available research evidence to aid clinical care—may have changed little, but what is best and how to apply the concepts in practice continue to develop. The 3rd ISEHC conference in Taiwan, November 2014, marked another step in the evolution of evidence based healthcare. On the opening plenary, I suggested six areas where EBM’s future attention was needed.

1. Don’t skip “step 0,” but foster doubt, uncertainty, and honesty
The “traditional” steps of EBM we teach students are: Ask, Acquire, Appraise, and Apply. However, Ian Scott—a physician in Brisbane—has suggested the most important step precedes these: recognizing our uncertainties. Without this “Step 0,” we cannot begin the other steps. Beginners often ask detailed convoluted questions. But with experience of uncertainty, we ask more basic questions about our everyday tests and treatments, and about the advice and information we are deluged by. However, we currently understand little of this step of recognizing our basic uncertainties. At McMaster, Sackett often exposed disagreement about clinical signs to raise the uncertainty about what is “correct.” Others simply reward students for saying “I don’t know,” instead of treating ignorance as an admission of failure. Both are excellent ideas, but, compared with the other steps of EBM, we have few ideas and almost no research on how best to do “step 0.” We need to do much more.

2. Beware overdiagnosis: our definitions are as important as our tests
For much of the brief history of EBM, we have taken diagnostic definitions for granted, using them as a starting point to study prognosis or treatment. However, definitions of disease often evolve over time: either incidentally—through improved technology such as spiral CT scans for pulmonary embolism—or through deliberate changes, such as the lowering of thresholds for diseases like diabetes, hypertension, or osteoporosis.

“Overdiagnosis” has been low on the EBM radar, but has grown to be one of the largest problems facing medicine. [1] As one example, take the 3-fold growth in the incidence of thyroid cancer in the USA, Australia, and other countries. Is that due to radiation or diet? Probably neither; more probably it is an epidemic of diagnosis, not an epidemic of cancer. Thyroid cancer mortality has remained unchanged. Even more dramatic is the 15-fold increase in thyroid cancer in South Korea which arose from the ease with which it was added to national screening programs. [2] Though less dramatic, most cancers have seen substantial rises in incidence which appear to be overdetection rather than true increases. Many other diseases have seen changes in definitions, with most expanding. A recent analysis of guidelines identified 14 changed disease definitions, of which 10 widened and only 1 narrowed the definition. [3] This overdiagnosis causes problems with interpretation of our evidence about the prognosis and treatment of diseases, as the spectrum has been changed and sometimes dramatically. However, overdiagnosis is such a threat to the sustainability of medicine, that it is a worthy EBM topic in its own right.

3. It is the patient’s decision: practise and teach Shared Decision Making alongside EBM
EBM has always expressed sympathy with the ideas of shared decision making (SDM). For example the Sackett textbook definition is: “Evidence-based medicine is the integration of best research evidence with clinical expertise and patient values.” But the step of shared decision making gets much less attention in our EBM textbooks and teaching than searching skills or critical appraisal. We need to be much more explicit about the “how to” and teach, as part of the steps of EBM, both generic shared decision making (“options talk” and “decision talk”) and the use of decision aids. A small step is to incorporate SDM into tutorials on critical appraisal. For example, after doing a critical appraisal, I often end with students doing a role play of explaining its meaning: one plays doctor, one plays patient; then we have feedback using “Pendleton rules”—from the “doctor,” then the “patient,” then everyone else; we then swap roles and go again. A similar process could also be done to practise the use of a decision aid. Taking SDM more seriously is not only a good thing in itself, but would also help overcome the common misconception of EBM as a rigid discipline which is not patient centred. [4]

4. Take non-drug interventions as seriously as pharmaceuticals
If there was a drug which reduced hospital re-admissions for patients with chronic airways disease by 70%; or cut invasive melanoma rates by 50%; or prevented 50% of malaria cases; or prevented 50% of breech births, we would clamour for access. But there are non-drug treatments that offer these benefits, yet are neglected: exercise (“pulmonary rehabilitation”), daily sunscreen, insecticide-impregnated bed nets, and external cephalic version (turning the baby via the mother’s abdominal wall). We neglect them partly because they are not available in a single collection, equivalent to a pharmacopoeia. [5] To avoid this availability bias, those working in EBM need to put more effort into non-drug interventions than drug interventions to redress the existing imbalance. The Royal Australian College of General Practitioners has piloted a Handbook of NonDrug Interventions but a global effort is needed to extend this to other disciplines and countries.

5. Build clinical practice “laboratories” to study translation and uptake
Courses in EBM usually spend most time on the theory and skills, but very little—or none—on how to integrate these skills into bedside care. Furthermore, the clinical practice of EBM tends to go unrecorded, remaining out of public view and discussion, which limits the exchange and evolution of methods. We need to better record, evaluate, and teach the different ways of “doing” EBM in the clinical setting. In a series of interviews at the CEBM in Oxford, I talked with a dozen leading EBM practitioners in different clinical disciplines. They had very different ways of going about EBM in paediatric oncology, perinatal medicine, surgery, emergency medicine, and general practice. Of course, there are necessary differences, but we may also learn and adapt by finding out the processes of others. We need to treat the methods for the efficient and effective bedside practice of EBM as seriously as we treat the methods for doing a systematic review. To do this, we will need “EBM laboratories” where we can readily observe, record, and analyse the process of using evidence in practice.

6. Invest long-term in automating evidence synthesis
The costs of gene sequencing have dropped dramatically in the last decade: more than 50% per year. This dramatic drop in cost was not chance, but a serious investment in doing sequencing faster, better, and cheaper. By contrast, the costs of evidence synthesis have been increasing as we have increased the rigour of the process. That cost is inhibiting the use and uptake of evidence in practice, with our information landscape littered with out-of-date systematic reviews. We need to dramatically speed up the processes through standardising, streamlining, and—most importantly—automating many of the dozen or so steps in doing a systematic review or other evidence synthesis[6]. It will take time and resources to achieve this—maybe reducing the time by 50% per year—but we need to ignore some of the specific review alligators and start draining the process swamp. Without this automation, we will fall further behind with reviews and updates. And that will mean such reviews are seen as less and less relevant to practice.

If I had my time again, I would have started on these sooner. But as a wise ecologist once said: the best time to plant a tree is 50 years ago, the second best time is today.


1. Glasziou P, Moynihan R, Richards T, Godlee F. Too much medicine; too little care. BMJ. 2013 Jul 2;347:f4247.
2. Ahn HS, Kim HJ, Welch HG. Korea’s thyroid-cancer “epidemic”–screening and overdiagnosis. N Engl J Med. 2014 Nov 6;371(19):1765-7.
3. Moynihan RN, Cooke GP, Doust JA, Bero L, Hill S, Glasziou PP. Expanding disease definitions in guidelines and expert panel ties to industry: a cross-sectional study of common conditions in the United States. PLoS Med. 2013 Aug;10(8):e1001500.
4. Hoffmann T, Montori VM, Del Mar C. The connection between evidence-based medicine and shared decision making. JAMA. 2014 Oct 1;312(13):1295-6.
5. Glasziou PP. Promoting evidence-based non-drug interventions: time for a non-pharmacopoeia? Med J Aust. 2009 Jul 20;191(2):52-3.
6. Tsafnat G, Dunn A, Glasziou P, Coiera E. The automation of systematic reviews. BMJ. 2013 Jan 10;346:f139.

Paul Glasziou is professor of Evidence-Based Medicine at Bond University, and chairs the International Society for Evidence-Based Health Care. His research focuses on improving the clinical impact of research. As a general practitioner, this work has particularly focused on the applicability and usability of published trials and systematic reviews.

Competing interests: None declared.

  • Huw Llewelyn

    You may be pleased to know that the issues which you highlight were addressed initially about 50 years ago! When I started in
    medical school, I set out to understand in mathematical terms the thought processes I was expected to use. This work was described
    in my staff MD thesis published in 1987, encouraged and sponsored by the late Professor Sir James Black FRS. In the
    introduction to my MD in 1987 I said that “the techniques for assessing the ability of diagnostic tests to predict which
    patients will benefit from a treatment are surprisingly weak. Powerful treatments may thus be given to the wrong patients or not given to those who would benefit.”

    The Oxford Handbook of Clinical Diagnosis is based on the work in the above MD (the latest edition being published in September 2014). It explains the diagnostic and decision making process to students and young doctors with 600 pages of examples. It also includes what you wish for in your 6 headings.

    (1) It explains how clinical uncertainty can be expressed using probability theory using a new theorem built upon the foundation of Bayes rule(which is not included hitherto in EBM).

    (2) It explainshow to arrive at treatment indication criteria and diagnostic criteria in a pragmatic, evidence-based way that minimizes over-diagnosis.

    (3) It explains how non-transparent intuitive diagnoses and decisions can be made transparent so that the patient, relatives, nurses and other doctors can join in during shared decision making.

    (4) It shows which treatments and advice are directed at each diagnosis, especially when there is multi-morbidity.

    (5) It suggests how degrees of certainty about the outcomes of clinical decisions can be ‘audited’ by calibrating them against observed success rates, thus turning every care setting
    into a clinical practice ‘laboratory’ (in the way that thoughtful doctors adjusttheir degrees of certainty with experience).

    (6) It explains how every clinical care setting can be used to do research by trying to replicate the findings of original research (as well as doing its own original research).

    My aim in doing this is to try to encourage doctors of the future to be more enlightened than previous generations. Perhaps this
    will bear fruit in 50 years time. However, I do not think we should make our patients wait 50 years. It would be best we did so today, as you say.

    I will be raising this at Evidence Live in Oxford this April 2015.