Understanding Evidence: Cochrane UK’s new series
Posted on October 3, 2016 by Martin Burton
Life is full of choices, and choice is important. Choosing different options when it comes to health care – particularly your own health care – is a serious matter. You don’t want to get it wrong.
Who needs to understand evidence?
I have sometimes thought that when patients are sitting in the waiting room of my outpatient clinic I should offer them a choice of consultation style. When they come and see me, do they want a rather old-fashioned, paternalistic, ‘doctor knows best’ type of consultation? One where I listen to them and then prescribe a treatment or other course of action. Or do they want the opposite; to be presented with a complete set of options and choices, a set of internet references and bundle of written materials so they can go away and make up their own minds.
In my view, the optimal consultation involves “shared decision-making”. One in which I and the patient together consider their options in the context of their values and beliefs and their attitude towards risk and uncertainty. Both of us need to understand the evidence relating to the decisions that are being made. Evidence for example about the effectiveness (or otherwise) of different treatments and the risks associated with those treatments. Evidence too about the accuracy of diagnostic tests and about prognosis. And perhaps sometimes – and maybe increasingly – evidence about the “cost-effectiveness” of different options.
All this requires a clear understanding of evidence. In a particular circumstance what is good evidence and what is bad? Indeed, what do we mean by ‘good’ and ‘bad’ in this situation. The term “evidence-based” is bandied around a lot these days. I suspect not always appropriately.
Towards a better understanding
We are launching a series of blogs to better help readers understand the use of evidence. The principles of evidence-based medicine dictate that ‘current best evidence’ should be brought to bear ‘conscientiously, explicitly and judiciously’ in making healthcare decisions.
‘Best evidence’ may come from a variety of sources. Systematic reviews of randomised controlled trials (RCTs) – such as those produced by Cochrane and published in the Cochrane Library – rank highest in the evidence hierarchy. Followed by RCTs themselves and then studies of other designs. Expert opinion and “mechanism-based reasoning” rank lowest. Understanding reports of systematic reviews, RCTs and other studies is critical. Unfortunately, just because something is published – on paper or on the internet – doesn’t mean you can believe it.
We hope this series will allow you to hone your skills so you can look critically at evidence and understand its strengths and weaknesses. A better understanding of evidence should – hopefully – allow you to make better choices about your own health care, or that of your family or patients. It should also help you, on a day-to-day basis, to look critically at news stories about health and to be rightly sceptical when things are labelled “evidence-based”.
Look out for our daily blogs this week and join in the conversation on Twitter with @mjburton @CochraneUK @Students4BE and @SarahChapman30 #understandingevidence