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Azithromycin therapy linked to small boost in cardiovascular mortality
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During 5 days of therapy, researchers found a small absolute increase in cardiovascular deaths. The increase was most pronounced among patients who had a high baseline risk for cardiovascular disease, according to new study data.
Researchers used data from a Tennessee Medicaid cohort to examine risk for death related to short-term antibiotic treatment. The cohort included 347,795 prescriptions for azithromycin (Zithromax, Pfizer);1,348,672 prescriptions for amoxicillin; 264,626 prescriptions for ciprofloxacin (Cipro, Bayer Healthcare); 193,906 prescriptions for levofloxacin (Levaquin, Janssen); and 1,391,180 prospensity-score–matched individuals who took no antibiotics (control periods).
Patients taking azithromycin for 5 days had an increased risk for cardiovascular death (HR=2.88; 95% CI, 1.79-4.63) and death from any cause (HR=1.85; 95% CI, 1.25-2.75) compared with patients taking no antibiotics. Researchers found no increased risk for death among patients taking amoxicillin. While the absolute number of deaths was low, relative to amoxicillin, there were about 47 more deaths per million courses of therapy in patients taking azithromycin (cardiovascular death: HR=2.49; 95% CI, 1.38-4.50; death from any cause: HR=2.02; 95% CI, 1.24-3.30). That risk increased to 245 additional cardiovascular deaths per million in patients in the highest decile of risk for cardiovascular disease. Patients taking azithromycin were at significantly greater risk for cardiovascular death vs. patients taking ciprofloxacin, but risk did not differ significantly from that of patients taking levofloxacin.
“We believe this study adds important information on the risk profile for azithromycin,” Wayne A. Ray, PhD, professor of preventive medicine at Vanderbilt University, said in a press release. “For patients with elevated cardiovascular risk and infections for which there are alternative antibiotics, the cardiovascular effects of azithromycin may be an important clinical consideration.”
Publication of these data prompted the FDA this week to issue a statement on azithromycin and risk for cardiovascular death. The agency is reviewing results of the study and will communicate any new information that results from the FDA review.
References:
- Ray WA. N Eng J Med. 2012;366:1881-1890.
Disclosures:
- Some researchers report consulting for XL Insurance and Swiss and providing expert testimony for Plaintiff Lawyers.
Perspective
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William Schaffner, MD
Azithromycin is among the most widely prescribed antibiotics, especially in ambulatory practice. It has a sufficiently broad antibacterial spectrum that has been used effectively to treat bronchitis, pneumonia, otitis and sore throats. It also has an acceptable safety profile. Patients find that taking a 'Z-Pak' 5-day course is appealingly convenient. However, this study by Ray and colleagues convincingly demonstrates that a 5-day course of azithromycin therapy is associated with a small increased risk for CV death among patients who have substantial underlying CVD. The study is a prime example of the sort of information about small serious risks in a defined population that can come only from the rigorous examination of very large databases. In this instance, patients receiving more than 347,000 courses of azithromycin were compared with several control groups ranging in size from more than 190,000 to more than 1,390,000 patients as a means of minimizing bias.
The results are definitive and also biologically coherent - two related antibiotics, erythromycin and clarithromycin, already are known to have similar risks. Now, what to do? Think twice before prescribing azithromycin to patients with congestive HF; patients who have had a prior infarction; patients who have had bypass surgery; or patients who have a stent. Indeed, think twice before prescribing any antibiotic. It is a sad truth that we physicians continue to prescribe antibiotics unnecessarily for viral infections. Often, the best therapy is reassurance and symptomatic care.
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