A Swedish cohort study shows that oral fluoroquinolone is associated with higher risks than is amoxicillin.
Fluoroquinolones are associated with tendinopathy and tendon rupture (NEJM JW Gen Med Jan 1 2013 and Am J Med 2012; 125:1228.e23). The presumed mechanism is stimulation of matrix metalloproteinase activity, which results in degradation of collagen and extracellular matrix structural components. Because excessive metalloproteinase activity also is involved in the pathophysiology of aortic aneurysm, Swedish researchers performed a registry-based study to explore a possible association between fluoroquinolone use and aortic aneurysm or dissection. About 306,000 fluoroquinolone treatment episodes (78% ciprofloxacin) were propensity score–matched to the same number of amoxicillin treatment episodes in middle-aged or older adults (age, ≥50).
Within 60 days of the date that a prescription was filled, rates of aortic aneurysm or dissection were 1.2 cases per 1000 person-years for fluoroquinolone and 0.7 cases per 1000 person-years for amoxicillin — a significant difference. The estimated absolute difference was 82 cases of aortic aneurysm or dissection by 60 days per 1 million treatment episodes.
Comment
This large study, in which confounding was minimized through propensity-score matching, adds to a growing body of evidence that fluoroquinolone use is associated with excess risk for aortic aneurysm or dissection. The results are biologically plausible given the mechanisms discussed above.
ARYAN'S BLOG 
A Swedish cohort study shows that oral fluoroquinolone is associated with higher risks than is amoxicillin.
Fluoroquinolones are associated with tendinopathy and tendon rupture (NEJM JW Gen Med Jan 1 2013 and Am J Med 2012; 125:1228.e23). The presumed mechanism is stimulation of matrix metalloproteinase activity, which results in degradation of collagen and extracellular matrix structural components. Because excessive metalloproteinase activity also is involved in the pathophysiology of aortic aneurysm, Swedish researchers performed a registry-based study to explore a possible association between fluoroquinolone use and aortic aneurysm or dissection. About 306,000 fluoroquinolone treatment episodes (78% ciprofloxacin) were propensity score–matched to the same number of amoxicillin treatment episodes in middle-aged or older adults (age, ≥50).
Within 60 days of the date that a prescription was filled, rates of aortic aneurysm or dissection were 1.2 cases per 1000 person-years for fluoroquinolone and 0.7 cases per 1000 person-years for amoxicillin — a significant difference. The estimated absolute difference was 82 cases of aortic aneurysm or dissection by 60 days per 1 million treatment episodes.
Comment
This large study, in which confounding was minimized through propensity-score matching, adds to a growing body of evidence that fluoroquinolone use is associated with excess risk for aortic aneurysm or dissection. The results are biologically plausible given the mechanisms discussed above.