Late-breaking abstract: Is the effect of inhaled adrenaline for in acute bronchiolitis modified by allergic disease?

Background Treating infant acute bronchiolitis is supportive, with no significant benefit by inhaled racemic adrenaline (iRA) over saline inhalations. It is unclear if treatment effect may differ in patients who develop atopic eczema (AE) or allergic sensitization (AS). We aimed to investigate if treatment effect of iRA in moderate to severe bronchiolitis in infancy was modified by atopic disease development of recurrent bronchial obstruction or atopic disease up to two years of age. Methods 294 of 404 children participating in a randomized controlled trial comparing the effect (length of hospital stay (LOS)) of iRA with inhaled saline were reinvestigated 18 months later including a structured, physician-led parenteral interview, clinical examination and a skin prick test (SPT) for 17 allergens. Analyses were performed with robust regression and stratified by atopic disease in case of significant interaction. Results Later AS and/or AE (n=77) interacted significantly (p=0.02) with LOS for iRA. Compared to saline, iRA treatment was associated with significantly shorter mean estimated LOS in patients with negative AS and AE at two years, (-13.9 hours (95% CI 1.4-26.5), p=0.003), but no significant differences were found in children with positive AE or AS(+16.2 hours (95% CI -43.3 to 11.0), p=0.24). The presence of recurrent bronchial obstruction (n=207) at two years of age did not influence the effect of adrenaline inhalations. Conclusions Children who by two years did not have allergic sensitization or atopic eczema had a significant benefit of adrenaline inhalations when hospitalized for acute bronchiolitis in infancy, suggesting that iRA may be efficient in some infants with bronchiolitis.