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Oral dexamethasone works better than oral prednisolone in children with croup

BMJ 2006; 333 doi: (Published 03 August 2006) Cite this as: BMJ 2006;333:0-e

Research question Is prednisolone as good as dexamethasone at relieving croup in children?

Answer No. Dexamethasone works better

Why did the authors do the study? Oral dexamethasone is an established treatment for childhood croup, reducing symptoms and helping keep children out of hospital. But in some countries, such as Australia, oral dexamethasone is commercially available as a tablet only, which is unsuitable for infants and many young children. Hospital pharmacies can make up dexamethasone elixir, but it is expensive and unavailable to general practitioners who see many infants with croup. These authors wanted to find out if prednisolone, which is widely available as an elixir, could be used instead. They specifically wanted to know if the two drugs had equivalent effects in young children with mild or moderate croup.

What did they do? The authors recruited 133 children with a mean age of 37 months into a double blind randomised controlled trial comparing a single oral dose of dexamethasone (0.15 mg/kg) with a single dose of prednisolone matched for potency (1 mg/kg). Both drugs were given as medicines that tasted identical, made up by a hospital pharmacy. The children all had mild or moderate croup, determined by a validated croup score, and were attending the emergency department of a single tertiary care paediatric hospital in Western Australia. They were observed regularly from randomisation until discharge. The authors telephoned parents a week to 10 days after discharge to find out if their child had needed any further medical attention for croup, including hospitalisation. This was their main outcome measure. Secondary outcome measures included duration of croup symptoms (again reported by parents), length of time spent in the emergency department, and use of nebulised adrenaline.

The authors defined equivalence as an absolute difference between treatment groups of between 0% and 7.5% for the main outcome measure, and did a power calculation to guide recruitment.

What did they find? Of the children given prednisolone, 29% (19/65), needed further unscheduled medical care, compared with 7% (5/68) of the children given dexamethasone. The absolute difference of 22% between the groups had 95% confidence intervals between 8% and 35%, well outside the authors' definition of equivalence. In fact, further analysis showed that dexamethasone worked significantly better than prednisolone (P < 0.01) on this measure. No side effects were seen in either group, nor was there any difference in duration of symptoms, or use of nebulised adrenaline (five in each group).

What does it mean? This study showed that a single dose of prednisolone does not work as well as a single dose of dexamethasone for children with mild or moderate croup. Doctors in emergency departments should not simply substitute one for the other, although the authors say that many do. Dexamethasone lasts substantially longer than prednisolone (half life 36-72 hours v 12-36 hours), which may explain why a one off dose worked better in these children. Trials testing a longer course of prednisolone should be done in places where dexamethasone elixir remains hard to come by.


Sparrow A, Geelhoed.G. Prednisolone versus dexamethasone in croup: a randomised equivalence trial. Arch Dis Childhood 2006;91: 580-3

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