Patient Safety
Corey Diamond, PharmD
Studies generally observe that about one-third of all direct oral anticoagulant (DOAC) prescriptions contain at least one dosing error. Could hospital practitioners benefit from pharmacist DOAC dosing consultations? A team of researchers at the University of Maryland Medical Center set out recently to answer this question, publishing the results of a pharmacist-to-dose DOAC pilot study from July of 2021 in the Journal of the American College of Clinical Pharmacy.
There is considerable variation with DOAC doses depending on the FDA-labeled indication. Despite the fact that DOACs are generally regarded as a safer alternative to warfarin for many of the same indications, the safety challenge for prescribers stems from matching the right dose to the right disease state. A patient’s age, weight, renal and hepatic functions, and other medications all must be considered with the appropriate dosing regimen as well. The researchers at the University of Maryland Medical Center were able to demonstrate that a pharmacist-led DOAC consultation protocol may help significantly reduce DOAC medication error rates.
Results of the program
Willeford and colleagues conducted a retrospective single-center cohort study that compared patient data 6 months prior and 6 months after implementation of their pharmacist DOAC dosing protocol. The study pooled data from over 500 admitted adult patients prescribed apixaban, rivaroxaban, or dabigatran for venous thromboembolism and/or atrial fibrillation indications only.
The authors’ primary outcome was the difference in the number of patients who were administered at least one erroneous DOAC dose preimplementation of the pharmacist dosing protocol versus postimplementation. The authors defined a DOAC dosing error as an error in dosing for indication or renal function, incorrect timing of administration, improper anticoagulant switching, presence of a major drug–drug interaction, or duplication in therapy.
Overall, 41 patients (16%) received an incorrect DOAC dose in the preimplementation phase versus 22 patients (8.9%) in the postimplementation phase, a statistically significant relative risk reduction of 44% with a number needed to treat of about 14.
The overall rate of error was 12.5% across the entire study period, with the most common errors being underdosing (6.2%), incorrect timing (2.0%), overdosing (1.6%), incorrect switching (1.6%), presence of major drug–drug interactions (0.8%), and duplication in therapy (0.4%). Although the study was not sufficiently powered to detect a difference in these rates, the researchers also found a 42% relative reduction in discharge DOAC prescription error after implementation of the program.
Other benefits
Despite the reduction in errors observed after the implementation of the pilot program, the residual 8.9% error rate still represents a significant safety deficit as well as an opportunity to improve both physician and pharmacist education.
“The results of our analysis have helped us target our educational efforts to focus on commonly overlooked or missed errors,” the authors stated in their article. “For example, the most common error involving DOACs is inappropriate underdosing, particularly in older adults and/or patients with renal dysfunction. Our findings demonstrated little change in the rate of underdosing before and after implementation of the protocol, which has been a point of emphasis for our ongoing educational efforts.”
The authors go on to mention that they have continued to observe errors related to drug–drug interactions, despite these being flagged by their institution’s EHR, as well as inappropriate transitions in therapy. All these observations have fed into their efforts to improve education initiatives at their institution.
The study’s lower rates of DOAC errors upon patient discharge is also encouraging, suggesting “that the impact of a pharmacist-driven inpatient DOAC service may influence outpatient DOAC errors too and is a potential area for future studies,” the study authors wrote.
The efficacy of this study’s pharmacist-driven protocol on clinical outcome rates such as bleeding, stroke, or embolisms remains unclear. However, it is a useful surrogate that reflects the clinical pharmacist’s ability to make an impact on reducing the risk of serious adverse events in the hospital setting for a high-risk drug class that is more complex than it initially seems. ■