Evaluation of Baseline QTc Interval and Azithromycin Prescribing in an Academic Medical Center
The use of azithromycin for its anti-inflammatory effect in chronic obstructive pulmonary disease, cystic fibrosis, and lung transplant recipients has increased significantly. Recently published data cited a rise in cardiovascular death in patients with azithromycin compared to other antibacterial agents. In response, the FDA released warnings regarding prescribing azithromycin in certain patient populations. Our main objective aimed to assess inpatient prescribing patterns for azithromycin and determine the potential risk for adverse cardiovascular events.
From October 1, 2012 through April 30, 2013, 1610 encounters were identified for inpatients ≥19 years of age prescribed azithromycin. One hundred patient encounters were randomly selected for evaluation. Information collected for each patient and included length of stay, reason for use, dose, duration of therapy, concomitant medications associated with QTc prolongation, culture data, telemetry charges, and baseline ECG. Patients were divided into three risk categories based on number of QTc prolonging medications ordered (Low = 1, Medium = 2-3, High ≥4) and were subsequently compared.
In the study, 79% of azithromycin use was empiric for the treatment of suspected infections, 20% as an anti-inflammatory agent, and 1% as culture directed therapy. Sixty-five percent of patients received a baseline ECG prior to prescribing azithromycin and 39 of 65 (60%) had borderline or abnormal QTc prolongation. Twenty patients were concurrently prescribed medications identified as having a major drug-drug interaction with azithromycin, with an average overlap of 4.5 days. Seventy-six patients were prescribed 2 or more QTc prolonging medications, and only 32 (42%) were monitored with telemetry.
In a randomly selected cohort of patients receiving azithromycin therapy, a majority of patients (76%) were prescribed 2 or more QTc prolonging agents, with telemetry ordered less than half of the time. Additional studies are necessary to determine the risk of such drug combinations. Given recent warnings issued by the FDA, enhanced education is necessary for providers regarding the potential for adverse cardiac events with prescribing azithromycin.
D. Kunz, None
C. Hoesley, None