Adrenaline (epinephrine) compared to selective beta-2-agonist in adults or children with acute asthma: a systematic review and meta-analysis

Baggott, C.; Hardy, J.; Sparks, J.; Sabbagh, D.; Beasley, R.; Weatherall, M.; Fingleton, J.

Background International asthma guidelines recommend against adrenaline administration in acute asthma unless associated with anaphylaxis or angioedema. However, administration of intra-muscular adrenaline in addition to nebulised selective {beta}2-agonist is recommended for acute severe or life-threatening asthma in many pre-hospital guidelines. We conducted a systematic review to determine the efficacy of adrenaline in comparison to selective {beta}2-agonist in acute asthma. Methods We included peer-reviewed publications of randomised controlled trials (RCTs) that enrolled children or adults in any healthcare setting and compared adrenaline by any route to selective {beta}2-agonist by any route for an acute asthma exacerbation. The primary outcome was treatment failure, as indicated by hospitalisation, stay >24hrs in emergency department, need for intubation, or death. Results Thirty-eight of 1,140 studies were included, involving 2,275 participants. Overall quality of evidence was low. There was significant statistical heterogeneity, I2=56%. The pooled odds ratio for treatment failure with adrenaline versus selective {beta}2-agonist was 0.99 (0.74 to 1.34), p=0.96. There was strong evidence that recruitment age-group was associated with different estimates of the risk of treatment failure; with studies recruiting adults-only having a lower risk of treatment failure with adrenaline. It was not possible to determine whether adrenaline in addition to selective {beta}2-agonist improved outcomes. Conclusion The limited evidence available suggests that adrenaline and selective {beta}2-agonists have similar efficacy in acute asthma and does not support the use of adrenaline in addition to selective {beta}2-agonists in acute asthma. There is a need for high-quality double-blind RCTs to address this issue. PROSPERO registration number CRD42017079472