Chapter 1
Why read papers at all?

Does ‘evidence‐based medicine’ simply mean ‘reading papers in medical journals’?

Evidence‐based medicine (EBM), which is part of the broader field of evidence‐based healthcare (EBHC), is much more than just reading papers. According to what is still (more than 25 years after it was written) the most widely quoted definition, it is ‘the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients’ [1]. This definition is useful up to a point, but it misses out a very important aspect of the subject – and that is the use of mathematics. Even if you know almost nothing about EBHC, you probably know it talks a lot about numbers and ratios! A few years ago, Trisha and Anna Donald decided to be upfront about this in our own teaching, and proposed this alternative definition:

Evidence‐based medicine is the use of mathematical estimates of the risk of benefit and harm, derived from high‐quality research on population samples, to inform clinical decision‐making in the diagnosis, investigation or management of individual patients.

The defining feature of EBHC, then, is the use of numbers derived from research on population samples to inform decisions about individuals. This, of course, begs the question ‘What is research?’ – for which a reasonably accurate answer might be ‘Focused, systematic enquiry aimed at generating new knowledge’. In later chapters, we explain how this definition can help you distinguish genuine research (which should inform your practice) from the poor‐quality endeavours of well‐meaning amateurs (which you should politely ignore). (As an aside, it has become fashionable to include qualitative research within EBHC, and we do cover this in chapter 12, but most people talking about EBM and EBHC are referring to research that generates numbers).

If you follow an evidence‐based approach to clinical decision‐making, therefore, all sorts of issues relating to your patients (or, if you work in public health medicine, issues relating to groups of people) will prompt you to ask questions about scientific evidence, seek answers to those questions in a systematic way and alter your practice accordingly.

You might ask questions, for example, about a patient’s symptoms (‘In a 34‐year‐old man with left‐sided chest pain, what is the probability that there is a serious heart problem, and, if there is, will it show up on a resting ECG?’), about physical or diagnostic signs (‘In an otherwise uncomplicated labour, does the presence of meconium [indicating fetal bowel movement] in the amniotic fluid indicate significant deterioration in the physiological state of the fetus?’), about the prognosis of an illness (‘If a previously well two‐year‐old has a short fit associated with a high temperature, what is the chance that she will subsequently develop epilepsy?’), about therapy (‘In patients with acute coronary syndrome [heart attack], are the risks associated with thrombolytic drugs [clot busters] outweighed by the benefits, whatever the patient’s age, sex and ethnic origin?’), about cost‐effectiveness (‘Is the cost of this new anti‐cancer drug justified, compared with other ways of spending limited healthcare resources?’), about patients’ preferences (‘In an 87‐year‐old woman with intermittent atrial fibrillation and a recent transient ischaemic attack, do the potential harms and inconvenience of thrombolytic therapy outweigh the risks of not taking it?’) and about a host of other aspects of health and health services.

Professor Sackett, in the opening editorial of the very first issue of the journal Evidence‐Based Medicine, summarised the essential steps in the emerging science of EBM [2]:

1. Convert our information needs into answerable questions (i.e. to formulate the problem).
2. Track down the best evidence with which to answer these questions – which may come from the clinical examination, the diagnostic laboratory, the published literature or other sources.
3. Appraise the evidence critically (i.e. weigh it up) to assess its validity (closeness to the truth) and usefulness (clinical applicability).
4. Implement the results of this appraisal in our clinical practice.
5. Evaluate our performance.

Hence, EBHC requires you not only to read papers but to read the right papers at the right time, and then to alter your behaviour (and, what is often more difficult, influence the behaviour of other people) in the light of what you have found. Sometimes, how‐to‐do‐it courses in EBHC concentrate too heavily on the third of these five steps (critical appraisal) to the exclusion of all the others. Yet, if you have asked the wrong question or sought answers from the wrong sources, you might as well not read any papers at all. And all your training in search techniques and critical appraisal will go to waste if you do not put at least as much effort into implementing valid evidence and measuring progress towards your goals as you do into reading the paper. A few years ago, Trisha added three more stages to Sackett’s five‐stage model to incorporate the patient’s perspective: the resulting eight stages, producing a context‐sensitive checklist for evidence‐based practice, which (like the other checklists in this book) is given in Appendix 1.

If we were to be pedantic about the title of this book, these broader aspects of EBHC should not even get a mention here. But we hope you understand that the book would be incomplete without the final section of this chapter (Before you start: formulate the problem), Chapter 2 (Searching the literature), and Chapter 16 (Applying evidence with patients). Chapters 3–15 describe step three of the EBHC process: critical appraisal; that is, what you should do when you actually have the paper in front of you. Chapter 20 deals with common criticisms of EBHC. The challenges of implementation are so complex that they needed a book of their own, How to Implement Evidence‐Based Healthcare [3].

If you want to explore the subject of EBHC on the Internet, you could try the websites listed in Box 1.1 (these were the top suggestions when we asked our X [formerly Twitter] followers which ones they found most useful). If you’re not ready for that yet, don’t worry at this stage, but do put learning to use web‐based resources on your to‐do list. Don’t worry either when you discover that there are over 1000 websites dedicated to EBM and EBHC; they all offer very similar material and you certainly don’t need to visit them all.

Box 1.1 Web‐based resources for evidence‐based medicine

BMJ Evidence‐Based Medicine Toolkit: a resource site maintained by this leading UK medical journal containing a wealth of resources and links for EBM, including links to critical appraisal checklists and statistical tools. https://bestpractice.bmj.com/info/toolkit

National Institute for Health and Care Excellence: this UK‐based website, which is also popular outside the UK, links to evidence‐based guidelines and topic reviews. www.nice.org.uk

The A–Z List of Evidence‐Based Medicine Resources: A one‐stop shop for various databases maintained by Dartmouth Libraries at Dartmouth College, Hanover, NH, USA, including PubMed, the Cochrane Database of Systematic Reviews and the Database of Abstracts of Reviews of Effectiveness (DARE): https://www.dartmouth.edu/library/biomed/guides/research/ebm‐az‐list.html

Why do people sometimes groan when you mention evidence‐based healthcare?

Critics of EBHC might define it as ‘the tendency of a group of young, confident and highly numerate medical academics to belittle the performance of experienced clinicians using a combination of epidemiological jargon and statistical sleight of hand’ or ‘the argument, usually presented with near‐evangelistic zeal, that no health‐related action should ever be taken by a doctor, a nurse, a purchaser of health services or a policymaker unless and until the results of several large and expensive research trials have appeared in print and approved by a committee of experts’.

Anyone who works face to face with patients knows how often it is necessary to seek new information before making a clinical decision. In general, we don’t put a patient on a drug without evidence that it is likely to work. Apart from anything else, such off‐licence use of medication is, strictly speaking, illegal. Surely we have all been practising EBHC for years?

Well, no, we haven’t. There have been a number of surveys on the behaviour of doctors, nurses and related professionals and, while things seem to be improving, performance still falls short. It was estimated in the 1970s in the United States that only around 10–20% of all health technologies then available (i.e. drugs, procedures, operations, etc.) were evidence‐based; that estimate improved to 21% in 1990. Studies of the interventions offered to consecutive series of...