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Azithromycin does not increase ventricular arrhythmia risk
The antibiotic azithromycin is not linked to an increased risk for ventricular arrhythmia — a potentially deadly form of irregular heartbeat, researchers said.
Their study, published in the Canadian Medical Association Journal, found no increased risk for the disorder in patients receiving azithromycin compared with those receiving amoxicillin, another common antibiotic.
“This finding suggests that the risk of for ventricular arrhythmia is more likely due to a person’s poor health and caused by their infection, rather than to azithromycin itself,” Gianluca Trifirò, MD, PhD, an assistant professor of pharmacoepidemiology at the University of Messina, Italy, said in a news release. “This finding was confirmed in several sensitivity analyses and replicated in single databases participating in the study.”
Azithromycin, which falls in the macrolides family of drugs, is mostly used to treat respiratory and urinary tract infections. At least one other macrolide — erythromycin — has been found to disrupt the heart’s normal rhythm, leading to ventricular arrhythmia.
Results from previous observational studies conflict with each other on whether azithromycin could be linked to the condition.
Trifirò and colleagues conducted a nested case-control study including more than 14 million patients newly using antibiotics in community settings. They were drawn from seven health care databases in Denmark, Germany, Italy, the Netherlands and the United Kingdom.
In all, 12,874 patients (0.1%) developed ventricular arrhythmia. Of those patients, 30 (0.2%) were taking azithromycin and were matched to 1,344 control patients.
The researchers found no significantly increased risk for ventricular arrhythmia in azithromycin users compared with amoxicillin users (OR = 0.94; 95% CI 0.50–1.77), and the risk decreased in recent (OR = 0.58; 95% CI 0.38–0.87) and past azithromycin users (OR = 0.52; 95% CI 0.37–0.73) compared with amoxicillin users.
In a pooled analysis, current azithromycin use was associated with a significantly higher risk for ventricular arrhythmia when compared with nonuse of any antibiotics (OR = 1.97; 95% CI, 1.35-2.86). However, there was no significant increase in risk among recent (OR = 1.12; 95% CI, 0.92–1.37) or past azithromycin users (OR = 1.10; 95% CI, 0.95–1.28) compared with nonusers.
“Given the upper limit of the 95% CI and the crude incidence rate of ventricular arrhythmia in the general population in all seven databases, we would expect at most 8.07 excess cases of ventricular arrhythmia to be associated with azithromycin use per 100,000 person-years compared with nonuse of antibiotics,” the researchers said.
They also warned that the results would not necessarily apply in hospitals.
“Findings from our study may not be directly extrapolated to the hospital setting because the health status of patients and the nature of antibiotic use in the community setting is likely to be very different,” they wrote. – by Joe Green
Disclosure: Please see the full study for a list of all authors’ relevant financial disclosures.