Azithromycin did not reduce the rate of severe exacerbations and lower respiratory tract infections in patients with severe asthma, but may benefit patietns with non-eosinophilic severe forms, a small randomized controlled trial found.
The double-blind, placebo-controlled trial in Belgium randomly assigned low-dose azithromycin (n=55) or placebo (n=54) as add-on treatment to combination therapy of inhaled corticosteroids and long-acting beta-two agonists for 6 months.
Results appeared in Thorax.
The rate of severe exacerbations and lower respiratory tract infections was not significantly different between the two treatment groups: 0.75 (95% CI, 0.55 to 1.01) in the azithromycin group versus 0.81 (95% CI, 0.61 to 1.09) in the placebo group (P=0.682).
But, azithromycin was associated with a significantly lower rate of severe exacerbations and lower respiratory tract infections than placebo in subjects with non-eosinophilic severe asthma (blood eosinophilia less than 200/µL): 0.44 (95% CI, 0.25 to 0.78) versus 1.03 (95% CI, 0.72 to 1.48) (P=0.013).
Azithromycin significantly improved scores on the Asthma Quality of Life Questionnaire, but there were no significant between-group differences in the score for the Asthma Control Questionnaire or for lung function.
Long-term treatment with azithromycin was associated with an increased proportion of macrolide-resistant oropharyngeal streptococci, but there was no evidence suggesting that colonization with macrolide-resistant organisms increased the risk of lower respiratory tract infections or pneumonia.
Researchers noted that the significant reduction in the severe exacerbations and lower respiratory tract infections in azithromycin-treated patients with non-eosinophilic severe asthma, possibly due to antibiotic properties or anti-inflammatory and immunomodulatory effects, warrants further study.