The Medicare claims database is a valuable resource that can be used to monitor for arrhythmogenic risk of QT-prolonging medications in older patients, according to the findings of a recent observational cohort study published in Drugs – Real World Outcomes.

Although premarketing requirements for testing are stringent, the risk of serious cardiac arrhythmias associated with QT-prolonging drugs is difficult to predict using physiological measurements or evaluation that occurs in preapproval clinical trials. Because of this, evaluating an observational study that includes Medicare claims data may detect the proarrhythmic risk of medications known to prolong the QT interval.

“We identified 17 QT-prolonging drugs with known risk of torsades des pointes (TdP) that were not used to treat cardiac arrhythmias,” the authors explained. The analysis included 8 short term use drugs (ciprofloxacin, levofloxacin, moxifloxacin, azithromycin, clarithromycin, erythromycin, fluconazole, ondansetron), 9 chronic use medications (citalopram, escitalopram, haloperidol, thioridazine, chlorpromazine, cilostazol, anagrelidehydroxychloroquine, donepezil), and 4 serotonin-norepinephrine reuptake inhibitors (SNRIs) and amoxicillin as study controls.

De-identified claims data of 1.2 million Medicare beneficiaries were obtained and 2 Cox regression analyses for short term and chronic use drugs was performed. “The primary outcome was a composite of ventricular arrhythmias and/or sudden death, identified by ICD diagnostic codes,” the authors stated. The effect of each study medication on outcomes was assessed independently. In addition to known risk factors for medication-induced arrhythmias, other covariates included patient characteristics and comorbidities.


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Findings revealed that an increased arrhythmogenic risk was detected in 82.3% of the study drugs (5 short term drugs and all 9 chronic use drugs), while all the controls were considered “risk neutral”. The authors reported that ciprofloxacin was found to be the safest of the fluoroquinolones. Additionally, data analysis revealed that compared with erythromycin, both azithromycin and clarithromycin were found to be “relatively safe.”

Study findings also showed that citalopram and escitalopram were associated with increased risk compared with SNRI controls. The risk with escitalopram was reported to be greater than with citalopram.

“Comorbidities associated with increased risk included ischemic heart disease, electrolyte imbalance, bradycardia, acute myocardial infarction, heart failure, and chronic kidney and liver disease,” the authors added.

Based on their findings, the authors concluded that the proarrhythmic risk of QT-prolonging medications can effectively be monitored using the Medicare claims database.

Reference

Fung KW, Baye F, Kapusnik-Uner J, McDonald CJ. Using Medicare data to assess the proarrhythmic risk of non‑cardiac treatment drugs that prolong the QT interval in older adults: An observational cohort study. Drugs Real World Outcomes. 2021; doi.org/10.1007/s40801-021-00230-1.