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Not Picket

Every paediatrician can spot a child with autism?

3 Mar, 15 | by Bob Phillips

‘Course everyone can spot a child with autism. It’s there in the MRCPCH textbooks right? Something about a lack of speech and gaze avoidance and repetitive behaviour. That must be pretty amenable to a spot diagnosis.

This is me being a little provocative because hopefully very few, if any paediatricians think like this. Hopefully we all know that the condition exists on a spectrum (autistic spectrum disorders right?) and that often a diagnosis can be challenging.

more…

A little bit of formula?

9 Jun, 13 | by Giordano Pérez-Gaxiola

milk

Exclusive breastfeeding is regarded by WHO and by most, if not all, paediatric academies, as the ideal for newborns and infants up to 6 months old. It is also recommended that breastfeeding begins as soon as possible after birth. That is why the small pilot study by Flaherman et al is both interesting and controversial.

Researchers randomised exclusively breastfed term newborns that had had 5%-10% weight loss before 36 hours, and were 24-48 hours old at time of recruitment, into two groups: The intervention group was syringe fed 10 ml of an extensively hydrolysed formula after each breastfeeding until mature milk production began; the control group was exclusively breastfed. Both groups were similar. Allocation was concealed. Blinding of parents and researchers was not possible, but the person who assessed outcomes was not aware of the assigned intervention.

The findings are interesting. It seems that infants in the early limited formula group had better outcomes. At 1 week, 2 of 20 infants in the intervention group had received formula in the preceding 24 hours, compared with 9 of 19 in the exclusive breastfeeding control group (risk difference 37%, 95%CI 3.4% to 71.0%). Also, infants in the control group received more formula than the intervention group during that first week. At 3 months, 15 of 19 infants in the intervention group were exclusively breastfed compared to 8 of 19 infants in the control group (risk difference -36.8%, 95%CI -65.6% to -8,1%, calculated from data in the article).

There are a few caveats, though. First, why use an extensively hydrolysed formula in the intervention group? Is it because the authors and/or the patients feel it is ‘less allergenic’ so it would be less likely to harm? Also, one of the authors has been employed by formula companies before. Should we be suspicious? Second, it is surprising that less infants from the control group, who began as exclusively breastfed, were exclusively breastfed at 3 months. Why? Maybe mums who feel they have failed their babies give up more. Researchers and trainers could not be blinded, so maybe there was a difference in how they treated or motivated each group. Lastly, the results, while statistically significant, are imprecise. Confidence intervals are very wide.

So, should be change practice and encourage mothers to give a little bit of formula while mature milk is produced? No. Maybe it won’t hurt, but this paper certainly doesn’t show that it helps. The findings of this study need to be replicated in a larger trial, preferably with independent funding and no conflicts of interest.

 

An odd way with odds ratio

26 May, 13 | by Ian Wacogne

 Can you spot anything wrong with this graph?

It’s from a paper in a major paediatric journal.  I’ve removed it from context, because for me it was a helpful lesson in spotting something important.  I’ve removed the labelling from the X axis, because I’m going to be a bit unkind about the paper, but in short it compares three different risk behaviours – the hatched box is the main behaviour (for example, cycling), and then the clear and black white boxes represent mutually exclusive subsets of that behaviour (for example, wearing lycra and not wearing lycra).  Then the three different clusters represent three possible outcomes, so the first group might be being struck by a car, the second might be caffeine consumption, and so on.)

Odds ratio

 

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When is a result not a result?

16 Nov, 11 | by Ian Wacogne

Hot on the heels of this great Archimedes on whether or not you should routinely do an LP in infants with a urinary tract infection, comes another publication, covered with a fairly critical review in Journal Watch.
What’s fascinating here is both “sides” drawing a conclusion that they can’t draw. more…

Probiotics here, probiotics there, probiotics everywhere

14 Nov, 11 | by Giordano Pérez-Gaxiola

Probiotics are everywhere these days. They are supposed to prevent all kinds of diseases, from infectious to immunological to allergic. Some of the claims have strong evidence, some not. A pilot study by Youngster I, et al, in which the role of probiotics before immunisations is studied, is yet another positive discovery, but there are several limitations that force us to be cautions and not overly excited about it. more…

What’s a normal CSF opening pressure?

19 Apr, 11 | by Ian Wacogne

Bob has kindly let one or two of us into his Archimedes blog to write about some of the papers we’ve consider for Picket in E&P

This letter in the NEJM (Avery RA, Shah SS, Licht DJ, et al. Reference range for cerebrospinal fluid opening pressure in children. N Engl J Med 2010;363:891-3.) gives us, potentially, a new set of reference ranges for CSF opening pressures in children and young people.  It’s got a bottom line as follows:

a post-hoc analysis of opening pressure percentiles was calculated for the 52 subjects who received minimal or no sedation and were not classified as obese, resulted in a 90th percentile of 25 cm of water

There are a number of things which are of note.

  1. Sedation does not seem to alter the CSF opening pressure.  This is at odds with what we’ve been led to believe previously.
  2. If the 90th centile is 25 cm of water, that’s a pretty big cut off for diagnosing and then treating raised intracranial pressure.  Are the authors seriously suggesting that 10% of all children have raised intracranial pressure?
  3. In their larger population, which includes sedated and obese children the 90th centile is at 28 cm water.  That’s a pretty high pressure, in the context of what I’ve previously understood.
  4. Their way of determining obesity is very strange indeed.  They seem to have taken an adult approach, with the assumption that a certain value of BMI indicates obesity.  However, we know that BMI normal range changes with age, and that in order to compare children over time and between ages, you need to look at BMI SDS – ie a mathematical representation of the centile for the age.
  5. BMI was only available on 131 of the 197 patients.
  6. The other bit they don’t give enough data on – even in the appendix – is the actual discharge diagnosis.  These are a series of diagnostic LPs, and they’ve done their best to exclude what would be reasonably expected to alter intracranial pressure – or specifically raise it.  However, the range discharge diagnoses is quite broad, from “headache” to “undiagnosed white matter disease”.

So, I think this is a flawed paper, and as such it doesn’t reach the threshold of quality we’d apply to Picket it.  However, it does give us some interesting information and food for thought.  Does it change my practice?  I suspect I might be a bit more permissive about slightly raised opening pressures.  In those children with “barn door” raised pressure, this will still be straightforward, but it doesn’t help me in treating children with some symptoms, but with an opening CSF pressure of, say, 27 cm water.  What would I do if I saw this tomorrow?  Probably an n=1 trial of therapy, and see what happened…

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