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.

Dear Doctor Letters regarding citalopram and escitalopram: guidelines vs real-world data

Dear Doctor Letters (DDLs, Direct Healthcare Professional Communications) from 2011 provided guidance regarding QTc-prolonging effects with risk of torsade de pointes during treatment with citalopram and escitalopram. This study examines the DDLs' effects on prescription behavior. Data from 8842 inpatients treated with citalopram or escitalopram with a primary diagnosis of major depressive disorder (MDD) were derived from a European pharmacovigilance study (Arzneimittelsicherheit in der Psychiatrie, AMSP) from 2001 to 2017. It was examined to what extent new maximum doses were adhered to and newly contraindicated combinations with QTc-prolonging drugs were avoided. In addition, the prescriptions of psychotropic drugs before and after DDLs were compared in all 43,480 inpatients with MDD in the data set. The proportion of patients dosed above the new limit decreased from 8 to 1% in patients ≤ 65 years and from 46 to 23% in patients > 65 years old for citalopram versus 14-5% and 47-31% for escitalopram. Combinations of es-/citalopram with other QTc-prolonging psychotropic drugs reduced only insignificantly (from 35.9 to 30.9%). However, the proportion of patients with doses of quetiapine > 150 mg/day substantially decreased within the combinations of quetiapine and es-/citalopram (from 53 to 35%). After the DDLs, prescription of citalopram decreased and of sertraline increased. The DDLs' recommendations were not entirely adhered to, particularly in the elderly and concerning combination treatments. This might partly be due to therapeutic requirements of the included population. Official warnings should consider clinical needs.

[Effect of the direct healthcare professional communication on citalopram and escitalopram drug utilization for inpatient treatment of anxiety disorders]

BACKGROUND

In 2011, direct healthcare professional communication (DHPC) letters on citalopram and escitalopram were sent out to address the risk of QTc prolongation in the ECG. Healthcare professionals were informed about a reduction of the maximum recommended daily dose. Furthermore, a contraindication for QTc-prolonging co-medication was given. Previous studies noted that these instructions were implemented incompletely.

AIM

For the first time, this study analyzed how the DHPC affected the prescription of citalopram and escitalopram in patients with anxiety disorders.

METHODS

Drug utilization data from the project "Arzneimittelsicherheit in der Psychiatrie e. V." (AMSP) was used to examine whether the proportion of patients treated with a higher-than-recommended daily dose ("high dose") and the proportion of patients with QTc-prolonging co-medication would decrease post-DHPC (combined category of citalopram/escitalopram).

RESULTS

Drug utilization data of n = 364 patients pre- and n = 262 patients post-DHPC were compared. The proportion of patients with high dose declined from 10.7% to 5.4% (p = 0.019). The proportion of patients with QTc-prolonging co-medication did not change significantly from pre- (54.7%) to post-DHPC (51.5%, p = 0.437).

DISCUSSION

In accordance with previous studies, the proportion of high-dose patients decreased after DHPC publication while the proportion of patients with QTc-prolonging co-medication remained widely unchanged. The specific recommendation on daily dosage seems to have been better implemented than the broadly formulated contraindication of QTc-prolonging co-medication. Hence, DHPCs should be written precisely and give advice for specific clinical situations.

The assessment of cardiac risk in patients taking lamotrigine; a systematic review

OBJECTIVE

The Food and Drug Administration (FDA) warned about lamotrigine's arrhythmogenicity based on in vitro data. This systematic review investigates lamotrigine's effect on cardiac conduction and risk of sudden cardiac death (SCD) in individuals with and without cardiovascular disease.

METHODS

We searched Web of Science and PubMed from inception through August 2021. We included studies measuring electrocardiogram (ECG) changes, laboratory abnormalities, or SCD among patients taking lamotrigine. Studies examining sudden unexpected death in epilepsy were excluded for scope. Two reviewers assessed articles and extracted data. We used the Effective Public Healthcare Panacea Project tool to evaluate confidence in evidence.

RESULTS

Eight randomized controlled trials, 9 nonrandomized observational studies, and 24 case reports were identified, with >3054 total participants, >1606 of whom used lamotrigine. One randomized trial of older patients found an average QRS increase of 3.5 +/- 13.1 ms. Fifteen studies reported no changes in ECG parameters. Case reports documented QRS widening (13), Brugada syndrome (6), QTc prolongation (1) and SCD (2), though many ingested toxic quantities of lamotrigine and/or other medications.

CONCLUSIONS

Evidence is insufficient to support the breadth of the FDA warning concerning lamotrigine's cardiac risk. Lamotrigine at therapeutic doses may be associated with modest, non-dangerous QRS widening.

Association between citalopram, escitalopram and QTc prolongation in a real-world geriatric setting

BACKGROUND

Although the US Food and Drug Administration (FDA) recommended upper limits for citalopram dosing in older adults due to risk of corrected-QT (QTc) prolongation, which was adopted, and extended to escitalopram by Health Canada, the scientific basis is unclear. The objective of this study was to assess the relationship between citalopram/escitalopram dosages and QTc interval in a real-world geriatric setting.

METHODS

We reviewed electronic health records at a university-affiliated geriatric health care center, over a 7-year period, to identify patients prescribed citalopram and escitalopram, who had an ECG within 90 days of initiation or dosage change. Linear regression analyses were conducted to assess the relationship between antidepressant dosage and QTc interval.

RESULTS

137 patients were identified (citalopram=97, escitalopram=40). No association was found between citalopram, escitalopram and QTc, in unadjusted or adjusted analyses. Among covariates, older age was significantly associated with QTc prolongation in the escitalopram group.

LIMITATIONS

Limitations to the current study include its retrospective design and the small sample size.

CONCLUSIONS

These data do not support the FDA or Health Canada's recommended maximum dosages of citalopram or escitalopram in the elderly. Therefore, for patients already on higher doses of these medications, the risk of QTc prolongation may not always outweigh the risk of dose lowering, such as relapse. Until larger prospective studies become available, the decision to comply or not with these federal agencies' recommendations should be weighed on an individual basis, taking into consideration all potential risk factors.