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Clashing concepts

2 Oct, 15 | by Bob Phillips

One thing I meet (fairly often) is the clash between the RCT and the patient ‘preference’. (I have to use ‘quotes’ because I know it’s the wrong phrase but I can’t find the right one.)

Take an example – topical anaesthesia for accessing implanted central lines in children & young people with cancer. For those who don’t know, nearly every child who needs chemo in Western Europe, North America and Australasia will have a surgically placed central line to enable venous access for blood taking and drug delivery. For some, it will be a ‘wiggly’ one, like a Hickman or Broviac. For some it will be an implanted one, like a Port-a-Cath or Pass-port. more…

Evidence free yet evidence based; guidelines again.

29 Sep, 15 | by Bob Phillips

2211526355_d11a0e29be_mIn a paper that I’d have never seen if it wasn’t for Twitter, Loes Knaapen of the Université de Montréal Public Health Research Institute reports the scholarly musings on a bunch of conversations with ‘EBM’ guideline developers, attendance at conference events, and a lot of reading around the subject of Guideline Creation. At the heart of these musings is the dilemma

‘how to address the challenges of providing evidence-based advice to address questions for which the evidence is lacking, of poor quality, immature or incomplete’


StatsMiniBlog: Stepped Wedge Trials

25 Sep, 15 | by Bob Phillips

calculator-97842_640You may be wondering about the phrase “Stepped Wedge Trial” (SWT) as there haven’t been many in paediatrics.

(There is quite a nice one about the provision of free school breakfasts though – showed that giving free breakfast didn’t really improve attendance, or test scores, but the children didn’t feel as hungry.)

They are a trial designed at evaluating interventions undertaken on ‘places’ or ‘populations’ – like classes of school children, or wards in a hospital – where you intend to stagger the introduction of an intervention you believe will be useful, but wish to measure either the size of benefit (pragmatic SWT) or work out why the intervention works, or doesn’t (exploratory SWT). You randomise the timing of introducing the intervention in the different areas, and measure elements throughout the study. more…

Guest Blog: Computer says wheeze (less)

22 Sep, 15 | by Bob Phillips

This guest blog from Munib Haroon takes up the challenge of turning the terror of technology to good…

As I write these words there is a debate currently underway about whether machine intelligence will eclipse ours in the coming decades [for one end of this debate go see James Cameron’s The Terminator] meanwhile another debate about how internet useage should be monitored by ISP’s to track terrorists and other bad folk is just about to take off. It seems that computer’s have both a use and abuse-ability. Another ‘baleful’ effect we all hear about is their contribution to the obesogenic environment – which in a nutshell is that, technology takes kids off the playing fields [“those which weren’t sold off in the eighties!” I hear someone cry] and sticks them in the living rooms leaving them to become obese.

Well here’s something positive for a change. more…

Sleep tight

18 Sep, 15 | by Bob Phillips

Every so often you bump into something that you didn’t know you didn’t know. That might make a massive difference to your (or someone else’s) life.

Well recently I was directed at this survival guide encouraging sleep to survive shift working and do it safely and securely.

For us.

The key points are:


But what if you miss a malignancy?

15 Sep, 15 | by Bob Phillips

There’s a big push in the UK to make ‘early diagnosis’ of cancer happen more often. The assumption is that diagnosis earlier will mean the disease has not spread, is more treatable, and will lead to a better outcome.

For many conditions, the stage at presentation does indeed link to outcome. In some conditions, there’s a clear natural history that allows you to ‘catch it early’ (cervical neoplasia for example). In others, the biology doesn’t work like that, and early doesn’t mean anything (take the example of neuroblastoma screening).

But what about acute leukaemia?



8 Sep, 15 | by Bob Phillips

That was the repeated phrase of my middle child’s obsessive bedtime reading for a while. Picture of police bikes, fire engines, ambulances, mountain rescue 4×4 and lifeboats.

In not one frame was the rescued individual entered into a clinical trial of therapy or diagnostics.

I guess that might have been asking a bit much, but is it also a bit much to ask for signed, informed consent with an appropriate time to reflect between information delivery and accession? If we worry about risk of bias in non-randomised trials, should the acuity of emergency studies make this even more important to get right?


Basics: Study Type

4 Sep, 15 | by Bob Phillips

So sometimes it’s obvious (the title says “: Randomised Controlled Trial” or “Systematic Review …”) but sometimes it’s just a bit tricky to work out what type of study you’re dealing with.

The very clever folks at the AHRQ also had that – and the inconsistency of how researchers name things – and so developed an exceptionally handy flow-chart to the Naming Of Things:


Hartling L, Bond K, Harvey K, Santaguida PL, Viswanathan M, Dryden DM. Developing and Testing a Tool for the Classification of Study Designs in Systematic Reviews of Interventions and Exposures [Internet]. AHRQ Methods for Effective Health Care. Rockville (MD): Agency for Healthcare Research and Quality (US); 2010 Dec. Report No.: 11-EHC007-EF. (


Whose values?

1 Sep, 15 | by Bob Phillips

I was reading a really fascinating article about microarray-based comparative genomic hybridisation. The authors – experts in the exploration and understanding of data that looks worrying like something from The Matrix – describe the way that such powerful genetic techniques can see what might be different about one child’s genes, and suggest groups in which the technique may be used.

When the aCGH comes back with a pathological variant, that then explains the diagnosis, I can see how this may alter treatment choices, make a difference to understanding prognosis (but maybe not – as we’re not sure that the ‘forme fruste’ versions always work the same as the face-slappingly-obvious ones, are we?) and give information for reproductive choices.

And if we find a ‘nothing’, then we’re also a further step into acknowledged uncertainty. But … more…

StatsMiniBlog: Confidence Intervals

28 Aug, 15 | by Bob Phillips

20140205-091454.jpg As its summer time & thoughts of exciting summer camps expanding skills, or time spent catching up with missed opportunities, or indeed just beer & strawberries, are filling our lives it seems appropriate to go entirely left field and explore confidence intervals.

Confidence intervals describe – in terms of interpretation – the range of values where we think the real truth lies (x% of the time – where the ‘x%’ is the number that sits before the CI)*

They are a measure of the precision of our estimate. They can described almost any quantity – the mean, odds ratios, test sensitivity …

Mostly we see 95% CI; this sort of corresponds to our desire for p-values of <0.05. We sometimes see 99% CI – even more sure the truth is in here – or occasionally 90% – wanting desperately to sell us a Thing, usually.


– Archi

* You’ll note that a 95% CI means we are WRONG 5% OF THE TIME



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