Everything has changed - Non-blanching rash in children

If you told me that nothing has changed for you this past twelve months, I'd be quite surprised.  This year has been a rollercoaster both in and out of work for every healthcare professional I know.  As a finishing touch to the year that has changed everything, I have one more bit of news for you that will change your practice.  Strap in.  This one is huge.

So how did we get there from where we used to be? - "Fever with non-blanching rash is meningococcal sepsis until proved otherwise."

It has long been recognised that this outdated adage has become obsolete in a population with effective meningococcal vaccination.  When it was first coined, the pre-test probability of meningococcal disease (MD) in a child with fever and non-blanching rash was around 1 in 5.  In an unvaccinated population, the 20% chance of MD is more than enough reason to have a "treat in every case" approach in the absence of a rapid diagnostic test.

Since the introduction of a very successful meningococcal vaccination program, the prevalence of MD has dropped dramatically.  The absolute number of cases of MD (the numerator) became a fraction of the pre-vaccination years.  We continued to see large numbers of children with fever and non-blanching rash (the denominator) but no-one was recording how many.

Enter the PiC study, (1) possibly the most significant academic publication of recent years regarding the management of the unwell child.  This large UK based multicentre prospective study did a couple of very important things.  Firstly, it collected data about the prevalence of meningococcal disease in children with fever and petechial rash.   The number that it found was, as we had all hoped and expected, small.   That number was about 1%.

That was only part of the clinically important information that the study produced.  After all, people might say that a 1/100 risk of MD is enough to justify the continued blind treatment of all such children.

What if you could safely tell who to treat and not to treat though?  The PiC study had enough information about clinical features and outcomes to be able to test the validity of any guideline.  They simulated what would happen if all the children in the PiC study were managed according to a guideline's algorithm.  This allowed them to see how sensitive and specific each guideline is.

The NICE guideline (2) recommends treatment of all febrile children with non-blanching rash.  So no surprises that the PiC study found the NICE approach to have 100% sensitivity but only 1% specificity.  99% of children treated in this way have unnecessary tests, treatment and time in hospital. 

Most major paediatric emergency departments in the UK have been deviating from the "treat every time" approach for many years.  Most centres have guidelines which use a combination of clinical assessment and the use of inflammatory markers to select which children will not be treated.  The PiC study also evaluated the sensitivity and specificity of 6 of these local guidelines.  What this showed was that these guidelines retained 100% sensitivity but improved specificity.  The best guideline (Barts London) achieved a specificity of 36%.  That means that a lot of children are safely avoiding unnecessary treatment and time in hospital.

If you are thinking that this is all very nice but changes nothing for the pre-hospital clinician, the best bit is still to come.  A guideline that wasn't included in the PiC study was the Sheffield Children's Hospital Emergency Department (SCHED) Handbook.  (I believe that the reason that it was not included at the time was that the guideline was being changed.)  The direction of that change was away from using inflammatory markers as part of the decision making process.  The SCHED (3) guideline uses pattern recognition and experienced decision making.  Blood tests are not a recommended part of the process outside of specific circumstances (e.g. diagnosing haematological cause).

Although this guideline is not one of those in the PiC study, it has since been applied to the PiC study dataset of 1300 children with fever and non-blanching rash.  The exciting result of this is that the Sheffield guideline also retains 100% sensitivity (95% CI 82-100%) but achieves an even higher specificity at 69% (95% CI 66-72%).  (3)

The exciting thing about this approach is that it is a decision that can be made anywhere.  What the decision is made up of is the following

• Continuing default treatment in a few cases (rare but important)
• Fever and purpuric rash
• Fever and petechial rash and clinically probable sepsis
• Identifying other possible causes (such as mechanical cause from vomiting) using pattern recognition to identify those at low risk
• For those children who do not have another diagnosis or deemed to need default treatment, allowing an experienced decision maker to choose whether to treat or discharge.

Here is an adapted flowchart from the Sheffield Children's Hospital Emergency Department Handbook:

The next question you might be asking yourself is, "Am I an experienced decision maker?" when it comes to the child with fever and petechial rash.  While there is no simple answer to this, the likey answer is yes if you have 5-10 years of postgraduate experience in a role that includes decision making about unwell children.

Everything has changed in the management of the well child with petechial rash and fever.  Thanks to vaccination and high quality research, we can take a very different approach and avoid overtreatment of what is now known to be a low risk clinical presentation.

Edward Snelson
@sailordoctor

References

1. Waterfield T, Maney J-A, Fairley D, Lyttle MD, McKenna JP, Roland D, Corr M, McFetridge L, Mitchell H, Woolfall K, Lynn F, Patenall B, Shields MD, Validating clinical practice guidelines for the management of children with non-blanching rashes in the UK (PiC): a prospective, multicentre cohort study, The Lancet, November 2020
2. NICE. Meningitis (bacterial) and meningococcal septicaemia in under 16s: recognition,diagnosis and management | Guidance and guidelines | NICE. 2015 [cited 2017 Oct 10]
3. Snelson E, Waterfield T, Testing the limits of pragmatism in children with fever and non-blanching rash, Correspondence, The Lancet March 2021