GP practices asked to check adrenaline autoinjector dose is right for children’s weight

Thousands of young patients are being put at risk because they have been prescribed an adrenaline autoinjector (AAI) device at too low a dose for their weight, an analysis of NHS data suggests.

The UK researchers called on GP practices to review children and teenagers who have been prescribed the devices and for an automatic flag to be added to computer systems to highlight the risk.

Young children should be prescribed a lower dose 150 μg device but once they reach 25-30kg, they should be moved to a higher 300 μg adrenaline dose, the researchers wrote in Clinical and Experimental Allergy.

Yet in the NHS there is no standardised mechanism to switch patients to the correct dose, they added.

Dispensing data for England between 2022 and 2024 showed almost 47,000 patients had received a lower strength 150 μg device in their most recent prescription.

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Cross-referencing this with average weight growth centiles, the team estimated up to one in five of those prescribed a 150 μg AAI device would have exceeded the threshold for moving to the higher dose, depending on the cut-off used.

If looking at age alone, as suggested by Resuscitation Council UK who advise switching at six years, almost 50% of those who currently receive a 150 μg device should actually have a 300 μg version, they reported.

This ‘non-standard’ prescribing of the low dose version was higher in areas of England with more deprivation, the team also found.

Conversely, ‘conservative estimates’ found only 67 children likely to be under 25 kg and 330 children likely under 30 kg who received a 300 μg dose.

The exact weight at which switching is suggested varies by manufacturer, they explained, but this national level analysis has highlighted ‘inconsistencies’ in dose among prescribing of AAIs which needs to be reviewed, they concluded.

Speaking with our sister title Pulse, study lead Dr Louise Michaelis, consultant paediatrician in immunology and allergy at Newcastle upon Tyne Hospitals NHS Foundation Trust, said automated safety procedures need to be put in place to stop children falling through the net.

By the ages of 12 and 14 years, 99.6% of the population exceed the 25 kg and 30 kg thresholds respectively, they pointed out.

But most patients would exceed the thresholds sooner given that 50% of the population exceed 25 kg and 30 kg at ages 8 and 10 years.

Over the past decade there has been a large rise in the number of patients prescribed AAIs, likely due to greater awareness and education on allergic diseases.

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Dr Michaelis, who is also vice president for services for the British Society of Allergy and Clinical Immunology, said the team was in discussions with NHS England about how to address the issue and add alerts to electronic record systems.

Primary care guidance also needs to be updated to make it clear when patients should be switched to the higher dose, the team recommended.

They suggested that patients dispensed EpiPen150 μg, with a switching weight of 25 kg should be reviewed at age 8, whereas those dispensed Jext or Emerade 150 μg, with a switching weight of 30 kg should be reviewed at age 10.

As a secondary safety net an automated flag should be embedded into primary care systems in England to alert healthcare professionals about low-dose prescribing in patients over 14 years old.

‘The numbers were quite shocking and I’m really hoping, when we look at the dashboard in another month, and then four months’ time, that we see that the numbers are coming down,’ Dr Michaelis said.

She added she regularly comes across patients who have not activated their prescription at all, which also needs to be addressed.

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There is a move to provide schools with AAI devices after figures showed less than half of schoolchildren in England who are at risk of a serious and potentially life-threatening allergic reaction to food had been prescribed one.

The potential saving to the NHS in England of pupils only needing one device if all schools had spare is currently being evaluated as part of a pilot scheme, the researchers noted, but this research also suggests better education and awareness is needed on dose.

A version of this article was first published by our sister title Pulse