Randomized double-blind controlled trial of roxithromycin for prevention of abdominal aortic aneurysm expansion

Background: Macrolide treatment has been reported to lower the risk of recu rrent ischaemic heart disease. The influence of macrolides on the expansion rate of abdominal aortic aneurysms (AAAs) remains unknown. The aim was to investigate the effect of roxithromycin on the expansion rate of small AAAs . Methods: A total of 92 subjects with a small AAA were recruited from two po pulations. One population consisted of 6339 men aged 65-73 years who were o ffered a hospital-based mass screening programme for AAA. From this populat ion 66 subjects were recruited. The remaining 26 men were recruited from am ong 49 subjects diagnosed at interval screening for an initial aortic diame ter between 25 and 29 mm. Subjects were randomized to receive either oral r oxithromycin 300 mg once daily for 28 days or matching placebo, and followe d for a mean of 1.5 years. Results: The mean annual expansion rate of AAAs was reduced by 43 per cent in the intervention group (1.56 mm per year), compared with 2.75 mm per yea r following placebo (P = 0.02). Multiple linear regression analysis showed that roxithromycin treatment and initial AAA size were significantly relate d to AAA expansion when adjusted for smoking, diastolic blood pressure and immunoglobulin A level of 20 enzyme immunounits or more. Logistic regressio n analysis confirmed a significant difference in expansion rates above 2 mm annually between the intervention and placebo groups: odds ratio = 0.09 (9 5 per cent confidence interval 0.01-0.75). Conclusion: In comparison to placebo, roxithromycin 300 mg daily for 4 week s reduced the expansion rate of AAAs.