You don't need to be signed in to read BMJ Group Blogs, but you can register here to receive updates about other BMJ Group products and services via our Group site.


Basics: Top 5 tips for evidence based paeds

5 Mar, 14 | by Bob Phillips

Hot on the heels of my office next door neighbours SoMe course we’re off with a ‘Top Tips’ post. (Anyone who hates the cheesy format can comment below or tweet us @ADC_BMJ.)

Please imagine a racing, 5-years-before-you’re-reading-this-pop-tune as your background music.

1. Know your question

Know what you’re asking. And know why you’re asking it. And know what you think the answer is, before you start looking.

2. Use sensible searches to crack high-quality resources

Don’t waste your life doing a systematic review that might well already have been done, appraised and packaged for you.

3. Appraise things using checklists to help you.

They help. They don’t command and control. And they are a Checklist, they are not The Inviolable Truth.

4. Decide what you think the answer actually is.

Do this on the basis of your appraisal. Now check back to what you thought the answer was (#1).

5a. If you’ve decided to do something – do it.


5b. If you’ve decided not to do something – think.

Are you actively not doing something? Or just not doing because you don’t believe the answer from #4? If so – how great would the evidence have had to be to press you from what you thought the answer was? Just how ‘anchored’ are you to your initial beliefs?

  • Archi


Diagnostic test accuracy

19 Feb, 14 | by Bob Phillips


The main things we look for when examining a new diagnostic test are “Is it as good as, or better than our usual one”, “Is it quicker?”, “Is it cheaper?” and “It is easier for patients/less dangerous?”

While the latter three questions can be assessed by asking the folk who do the test, asking the managers who pay for the test, and undertaking an adverse effects systematic review, it’s the first of these that we tend to call “diagnostic test accuracy”, and as clinicians we want to look for “phase III” studies.

The premise of such studies is that we can evaluate how accurate a test is by comparing its results with that of a ‘reference standard’ – a thing by which we will judge if the patient really does, or really doesn’t, have the diagnosis in question* – in a group of patients in whom we want to know the answer.


Differential Diagnosis

16 Feb, 14 | by Bob Phillips

The essential elements of a differential diagnosis study are, like most of critical appraisal, really simple and straightforward.

You need to start with a bunch of children/young people who turn up with the symptom, or symptom-complex, you’re interested in. Ideally, you need these folk to not already be known to have something, to attend a similar type of facility (e.g. office for general practitioners, or ED for ED types), and to be a consecutive group or random sample.

Things ‘ain’t what they used to be.

9 Feb, 14 | by Bob Phillips


Grandma says it. Great-grandpa says it. Even the wife’s starting to say it.

Its it true? Are things just not as good as they used to be?

Well, while we will leave the greater political discussions to others (except to note the falling child mortality rates in most countries) we can focus on how drugs seem to be less effective over time. And not just antibiotics.


Testing. Diagnostic tests – why?

5 Feb, 14 | by Bob Phillips


“But what’s wrong with him, doctor?”

The constant refrain from many a consulting room is not “How can you make her better?” but “Can you name the problem so I can own and understand it?”. When addressing this need we will each develop our  own approaches; some of us will explore differentials, others state the top of our list, others delve into the concerns sitting behind the inquiry. When addressing the content – what’s actually wrong – we’ll probably want to come up with a diagnosis.


Basics. How much is enough?

26 Jan, 14 | by Bob Phillips

We’ve approached EBM by thinking about it as a framework for thinking, not a checklist to tick though.

It’s the combination of patients views, clinical expertise and relevant research. The process is of asking, acquiring, appraising, applying and assessing.

But when it comes to applying evidence to answer a question – how much is enough? more…

Basics. RR, OR and the like

12 Jan, 14 | by Bob Phillips

Just a few posts ago, we introduced the idea of NNT as being an ‘absolute’ measure of how effective a treatment is; that is, the number of folk needed to treat to get one extra good result, compared to something else. This can be used to balance against stuff that might be negative – such as side effects, or costs/resource uses.

An alternative way of measuring effectiveness is to look at the relative efficacy, with measures such as relative risks or odds ratios.


How much should we believe in autonomy?

8 Jan, 14 | by Bob Phillips

We’ll all remember that we are meant, with grown-ups, to allow the patient to make a choice about their care. When the patient is not really due to be in the atmosphere for another 2 months, and hasn’t quite learned to open its eyes rather let alone discuss UVC vs Groshong lines, then we’re sort of let-off that problem.

But we do have a large number of patients with the ability to make the choices about their care: may of them are teenagers. And for those who aren’t able, many will have parents or carers who may wish to be involved in decisions. How should we progress with this?

The classical model of decision making would oppose paternalism (“Take this medicine”) against choice (“This medicine might help. It might not. Take it if you want.”) But a not-so-recent article by @EntwistleV on the nature of health screening choices offers a further option, which works to describe a route where a “recommendation” is offered. This works to balance information delivery about a healthcare decision, allowing autonomy, with the expert opinion of the clinician. This is the basis of an informed discussion which then works more explicitly to combine the three aspects we know are at the heart of EBM: research evidence, clinical expertise and patient preferences.

(It’s behind a paywall but worth seeking out a friendly academic if you want to read the whole thing, Thoroughly worth it.)

- Archi

Basics. NNT

5 Jan, 14 | by Bob Phillips

The NNT – number needed to treat – is thought by many to be a central core of EBMing. (I’d argue that the numbers in EBM are only a small part of the equation – and that understanding the question and the biases inherent in the study design are greater – but I’d still agree it’s important.)

So – what’s the NNT?


Basics: Where’s the art of medicine in EB medicine?

22 Dec, 13 | by Bob Phillips

It’s suggested, often by those who are faced with EBM as a rather coarse stick waved to stop them acting in one way, or to force them to act in another, that practicing EBM destroys any ‘art’ in medicine.

I’d argue that it integrates and emphasises the need for art. The three-ringed combination of good quality science, a clear understanding of our expertise in delivery and a requirement to share the information and decision making processes with our patients, their parents (or all of them) makes clear that the ‘arts’ of communication, interpretation, and facilitation are essential. Any anyone who uses a guideline without seeing the GUIDE of the line it describes is failing their patients. (I’ve not found any evidence for this yet — but I do believe that if a guideline achieved >95% compliance then it’s either a technical SOP or someone’s doing it wrong and not spotted the patient that needed to be treated differently.)

There is science in each of our ‘arts’, like diagnosis. And some of these arts are teachable. But the essential part of all these ‘arts’ is that they require mastery by practice. So become EBM masters, and practice away, using arts to be guided by science to deliver excellent care.

- Archi

ADC blog homeapage

ADC Online

Education, debate, and meandering thoughts on child health, using evidence and research.Visit site

Latest from Archives of Disease in Childhood

Latest from Archives of Disease in Childhood

Latest Paediatrics jobs

Paediatrics jobs