Maybe Fluoroquinolone, Dissection Risk Isn’t True

October 20, 2020

Written by Clay Smith

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This study calls into question the association of fluoroquinolone antibiotics with aortic aneurysm/aortic dissection (AA/AD).

Why does this matter?
Fluoroquinolone (FQ) antibiotics have been associated with tendon rupture, hypoglycemia, altered mental status, QT prolongation, and sudden death. There were already a lot of reasons to hate. Then studies in BMJ and JACC found that FQ use was associated with AA/AD. It was just too much…but wait. Could there have been confounding by indication, since those who receive FQs also receive imaging studies more often?

So, maybe FQs don’t make aortas explode…
This was a large U.S. insurance database study using propensity matching for 85 possible confounders. They found that AA/AD was associated with use of a FQ vs azithromycin for pneumonia (HR 2.57; 95%CI 1.36-4.86) but not when comparing a FQ vs TMP/SMX for UTI (HR 0.99; 95%CI 0.62-1.57). Now that’s weird. It seems more likely that there was an unrecognized confounder. They also compared a FQ cohort to matched patients receiving amoxicillin and found the incidence was extremely low, <0.01% in both, yet there was a slight increased risk for AA/AD in the FQ cohort: HR 1.54 (95%CI, 1.33-1.79). However, when they looked at patients who had baseline imaging prior to antibiotics and had no detectable AA/AD, the association was no longer significant; HR 1.13 (95% CI 0.96-1.33). This raises the concern of confounding by indication (yes, there really is a site called Catalogue of Bias, which makes JournalFeed look racy by comparison).

Another study in the same issue of JAMA Internal Medicine was a case-control and found certain infections were associated with AA/AD but did not find an association between FQ use and AA/AD. They concluded that septicemia or intra-abdominal infection was likely what increased risk of AA/AD and not the FQ.

Sources
Association of Fluoroquinolones With the Risk of Aortic Aneurysm or Aortic Dissection. JAMA Intern Med. 2020 Sep 8. doi: 10.1001/jamainternmed.2020.4199. Online ahead of print.
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Association of Infections and Use of Fluoroquinolones With the Risk of Aortic Aneurysm or Aortic Dissection. JAMA Intern Med. 2020 Sep 8. doi: 10.1001/jamainternmed.2020.4192. Online ahead of print.
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