The CredibleMeds® list: Usage of QT interval prolonging drugs in Germany and discordances with prescribing information

Low Risk of Cardiac Complications during Long-Term Follow-Up of Opioid Dependence

OBJECTIVES

To prospectively assess rates of QT prolongation, arrhythmia, syncope, and sudden cardiac death (SCD) in a cohort of people with heroin dependence.

METHODS

To estimate rates of QT prolongation, arrhythmia, and syncope, a subcohort (n = 130) from the Australian Treatment Outcomes Study, a prospective longitudinal cohort study of 615 people with heroin dependence, underwent medical history, venepuncture, and ECG at the 18- to 20-year follow-up.To estimate rates of SCD, probabilistic matching for the entire cohort was undertaken with the Australian Institute of Health and Welfare National Death Index. Deaths were classified into suicide, accidental overdose, trauma, unknown, and disease, which were then further subclassified by probability of SCD. SCD rate was the number of possible or probable SCDs divided by total patient years from the cohort.

RESULTS

From the subcohort, 4 participants (3%) met the criteria for QT prolongation; 3 were prescribed methadone. Seven participants (5%) reported history of arrhythmia, including 2 transferred from methadone to buprenorphine. Thirty participants (23%) reported a previous syncopal event-14 diagnosed as nonarrhythmic syncope and 13 not investigated. In the previous 12 months, 66 participants (51%) reported heroin use; 55 participants (42%) were prescribed methadone. No participant had QTc greater than 500 milliseconds.There were 3 possible SCDs, translating to an estimated SCD rate of 0.29 (CI: 0.05, 0.8) events per 1000 patient years. More cohort members died of overdose (n = 50), suicide (n = 11), and hepatitis C (n = 4).

CONCLUSIONS

Low rates of QT prolongation, arrhythmia, syncope, and SCD in the cohort despite high rates of heroin use and methadone treatment.

Evaluating the prescribing and monitoring of medications associated with QTc-prolongation in the ambulatory care setting

RATIONALE

Little is known about the prescribing of medications with potential to cause QTc-prolongation in the ambulatory care settings. Understanding real-world prescribing of QTc-prolonging medications and actions taken to mitigate this risk will help guide strategies to optimize safety and appropriate prescribing among ambulatory patients.

OBJECTIVE

To evaluate the frequency of clinician action taken to monitor and mitigate modifiable risk factors for QTc-prolongation when indicated.

METHODS

This retrospective, cross-sectional study evaluated clinician action at the time of prescribing prespecified medications with potential to prolong QTc in adult patients in primary care. The index date was defined as the date the medication was ordered. Electronic health record (EHR) data were evaluated to assess patient, clinician and visit characteristics. Clinician action was determined if baseline or follow-up monitoring was ordered or if action was taken to mitigate modifiable risk factors (laboratory abnormalities or electrocardiogram [ECG] monitoring) within 48 h of prescribing a medication with QTc-prolonging risk. Descriptive statistics were used to describe current practice.

RESULTS

A total of 399 prescriptions were prescribed to 386 patients, with a mean age of 51 ± 18 years, during March 2021 from a single-centre, multisite health system. Of these, 17 (4%) patients had a known history of QTc-prolongation, 170 (44%) did not have a documented history of QTc-prolongation and 199 (52%) had an unknown history (no ECG documented). Thirty-nine patients (10%) had at least one laboratory-related risk factor at the time of prescribing, specifically hypokalemia (16 patients), hypomagnesemia (8 patients) or hypocalcemia (19 patients). Of these 39 patients with laboratory risk factors, only 6 patients (15%) had their risk acknowledged or addressed by a clinician. Additionally, eight patients' most recent QTc was ≥500 ms and none had an ECG checked at the time the prescription was ordered.

CONCLUSION

Despite national recommendations, medication monitoring and risk mitigation is infrequent when prescribing QTc-prolonging medications in the ambulatory care setting. These findings call for additional research to better understand this gap, including reasons for the gap and consequences on patient outcomes.

Development in Prescriptions of Contraindicated and Potentially Harmful QT Interval-Prolonging Drugs in a Large Geriatric Inpatient Cohort From 2011 to 2021

Regulatory authorities put major emphasis on QT (interval)-prolonging properties of new molecular entities. Product information/Summaries of Product Characteristics (SmPCs) of multiple drugs contain warnings or contraindications regarding QT prolongation, e.g., on coadministration of QT-prolonging drugs (QT drugs). To characterize the development of the QT drug burden, we performed a trend analysis of prescriptions and co-prescriptions of QT drugs in a large geriatric inpatient cohort. The German SmPCs (status of 2014 and of 2021) and the year-wise listings in the CredibleMeds^® database from 2011 to 2021 were used as sources. There were 402,631 geriatric cases included. The group of QT drugs according to SmPCs in 2014, which must not be combined with other QT drugs, was less frequently involved in contraindicated co-prescriptions in 2021 compared with 2015 (3.0% (2.5-3.7%) of cases with at least one of those drugs in 2021 vs. 4.0% (3.5-4.5%) in 2015), with citalopram, escitalopram, and amiodarone involved in nearly 90% of the co-prescriptions. The number of CredibleMeds-QT-drugs per patient increased from 0.4 (SD=1.1) in 2011 to 1.8 (SD=3.9) in 2021. The percentage of contraindicated co-prescriptions of drugs with known risk for torsade de pointes according to CredibleMeds^® listings at the beginning of the respective years increased from 1.7% in 2011 to 6.1% in 2021. Considering the regularly updated CredibleMeds^® QT drugs list, the contraindicated co-prescriptions of QT drugs markedly increased in the last decade. If prescribers considered only the few most frequently (co-) prescribed QT drugs, then most of the medication errors regarding QT drugs could be prevented.