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Comparison of Cardiac Events Associated With Azithromycin vs Amoxicillin
Haridarshan Patel1, Gregory S Calip1,2, Robert J DiDomenico1,3
1Department of Pharmacy Systems, Outcomes, and Policy, College of Pharmacy, University of Illinois at Chicago.
Insights
This study found azithromycin use did not increase cardiac events compared to amoxicillin, except when combined with QT-prolonging drugs. Clinicians should exercise caution in such cases.
Area of Science:
- Pharmacovigilance
- Cardiology
- Real-world evidence studies
Background:
- Conflicting evidence exists regarding the association between azithromycin use and cardiac events.
- Understanding this association is crucial for patient safety.
Purpose of the Study:
- To compare the risk of cardiac events in new users of azithromycin versus new users of amoxicillin.
- To investigate potential risk factors and patient subgroups associated with azithromycin use and cardiac events.
Main Methods:
- Retrospective cohort study using the Truven Health Analytics MarketScan database (2009-2015).
- 1:1 matching of new azithromycin users with new amoxicillin users using high-dimensional propensity scores.
- Cardiac events (syncope, palpitations, ventricular arrhythmias, cardiac arrest, death) were assessed at 5, 10, and 30 days post-initiation.
Main Results:
- No significant difference in cardiac events between azithromycin and amoxicillin users at 5, 10, or 30 days.
- Increased odds of cardiac events (OR 1.40) observed with azithromycin in patients concurrently using QT-prolonging drugs.
- No increased risk was found in older patients or those with pre-existing cardiovascular conditions.
Conclusions:
- Azithromycin is generally safe regarding cardiac events when compared to amoxicillin.
- Concurrent use of QT-prolonging drugs necessitates careful consideration of azithromycin prescription.
- Real-world data supports a favorable cardiac safety profile for azithromycin in most patient populations.
Importance:
Conflicting evidence exists on the association between azithromycin use and cardiac events.
Objective:
To compare the odds of cardiac events among new users of azithromycin relative to new users of amoxicillin using real-world data.
Design, Setting, And Participants:
This retrospective cohort study used data from Truven Health Analytics MarketScan database from January 1, 2009, to June 30, 2015. Patients receiving either amoxicillin or azithromycin and enrolled in a health care plan 365 days before (baseline period) the dispensing date (index date) were included in the study. Patients were matched 1:1 on high-dimensional propensity scores. Data were analyzed from October 1, 2018, to December 31, 2019.
Exposures:
New use of azithromycin compared with new use of amoxicillin.
Main Outcomes And Measures:
The primary outcome consisted of cardiac events, including syncope, palpitations, ventricular arrhythmias, cardiac arrest, or death as a primary diagnosis for hospitalization at 5, 10, and 30 days from the index date. Logistic regression models were used to estimate odds ratios (ORs) with 95% CIs.
Results:
After matching, the final cohort included 2 141 285 episodes of each index therapy (N = 4 282 570) (mean [SD] age of patients, 35.7 [22.3] years; 52.6% female). Within 5 days after therapy initiation, 1474 cardiac events (0.03%) occurred (708 in the amoxicillin cohort and 766 in the azithromycin cohort). The 2 most frequent events were syncope (1032 [70.0%]) and palpitations (331 [22.5%]). The odds of cardiac events with azithromycin compared with amoxicillin were not significantly higher at 5 days (OR, 1.08; 95% CI, 0.98-1.20), 10 days (OR, 1.05; 95% CI, 0.97-1.15), and 30 days (OR, 0.98; 95% CI, 0.92-1.04). Among patients receiving any concurrent QT-prolonging drug, the odds of cardiac events with azithromycin were 1.40 (95% CI, 1.04-1.87) greater compared with amoxicillin. Among patients 65 years or older and those with a history of cardiovascular disease and other risk factors, no increased risk of cardiac events with azithromycin was noted.
Conclusions And Relevance:
This study found no association of cardiac events with azithromycin compared with amoxicillin except among patients using other QT-prolonging drugs concurrently. Although azithromycin is a safe therapy, clinicians should carefully consider its use among patients concurrently using other QT-prolonging drugs.
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