Thursday, 17 April 2014

Single dose dexamethasone for asthma?


In the chaos of the Emergency Department, I love to keep things simple. Nothing makes me happier than to be able to give a single dose of a drug to cure a particular condition. No need for a prescription and no need to worry about medication non-compliance. Acute exacerbations of asthma are such a ubiquitous presentation that I have longed hoped that a single dose of dexamethasone would be sufficient to effect a cure in suitable outpatients. I have been looking for data to support my “hypothesis” for some time now. Perhaps we have found it in the form of a recent systematic review and meta-analysis published in the journal Pediatrics.

Six randomized trials were identified after an explicitly defined search of Medline looking at dexamethasone vs. prednisone/prednisolone for the outpatient treatment of asthma. The primary outcome was return visits or hospital readmissions. As is the potential weakness of meta-analysis, there was some heterogeneity in the studies identified. Dexamethasone was given as a single IM dose in 3 studies, as a single oral dose in 1 study and as multiple oral doses in 2 studies. Therefore combining them may be problematic.

Nevertheless, there were no differences in relative risk in the primary outcome and the conclusion was “practitioners should consider single or 2-dose regimens of dexamethasone as a viable alternative to 5 days of prednisolone/prednisone.”

The whole point of a meta-analysis is to combine similar smaller studies in order to have greater statistical power to detect differences between groups. In addition, this greater number gives you better point estimates, narrow confidence intervals and allows you to look at subgroups that may have been impossible had the studies not been combined. Unfortunately this meta-analysis only included ONE small study with 117 patients that gave a single dose of oral dexamethasone (0.6mg/kg up to 18mg). Perhaps the jury is still out.

Whats the bottom line? I like the conclusion. I like the fact that it is printed in pretty font in a high impact journal. This may provide me with greater confidence (perhaps bravado) when prescribing a single dose of dexamethasone for outpatient asthma. But the monkey on my back has me worried that there still is a lack of high quality evidence to support this practice. A single large good quality RCT will trump a meta-analysis any day. Can someone please chuck a banana to the monkey and conduct a large RCT?

Covering:

Keeney, GE, Gray MP, Morrison AK, et al. Dexamethasone for Acute Asthma Exacerbations in Children: A Meta-analyisis. Pediatrics 2014;133:493-499

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