Intermittent Roxithromycin for Preventing Progression of Small Abdominal Aortic Aneurysms: Long-Term Results of a Small Clinical Trial

Background: Antibodies against Chlamydia pneumoniae are associated with an increased rate of expansion of small abdominal aortic aneurysms (AAAs). Short-term follow-up trials have shown a transient reduction AAA growth rate, in macrolide treated compared with placebo. Therefore we analysed the influence of intermittent, long-term roxithromycin treatment on AAA expansion and referral for surgery. Methods: Eighty-four patients with small AAAs were randomized to either an annual 4 weeks’ treatment with roxithromycin or placebo, and followed prospectively. Results: Intermittent, long-term Roxithromycin-treatment reduced mean annual growth rate by 36% compared with placebo after adjustment for potential confounders. Long-term roxithromycin-treated patients had a 29% lower risk of being referred for surgical evaluation, increasing to 57% after adjusting for potential confounders. Conclusion: Annual 4 week treatment with 300 mg roxithromycin daily may reduce the progression of small AAAs, and later need for surgical repair. However, more robust studies are needed for confirmation.