Pharmacist-Led DOAC Monitoring Improves Dosing

Introduction

In the United States, it is predicted that more than 6 million patients are treated with an anticoagulant.¹ In recent years, there has been a greater trend toward initiating patients on direct oral anticoagulant therapy (DOAC) or converting therapy from a vitamin K antagonist (VKA) to a DOAC. From 2011 to 2020, the rate of DOAC use in the US has steadily increased from 4.7% to 47.9%, whereas use of VKA has decreased from 52.4% to 17.7%.² The trend toward increased use of DOAC therapy has been most prominent for the treatment or prevention of cardiovascular conditions such as venous thromboembolism (VTE) and non-valvular atrial fibrillation (NVAF).³

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Though DOAC therapy is beneficial to treat or prevent various complications, there is a risk of bleeding associated with use of DOACs and dose adjustments or a change in therapy may be necessary during treatment to reduce this risk. During DOAC therapy, it is recommended to monitor renal and liver function, hemoglobin, weight, and adverse events to ensure any necessary adjustments to therapy based on findings. Current Novant Health policy recommends assessment of patient adherence (including insurance coverage and cost of DOAC), serum creatinine, age, weight, and complete blood count (CBC) at baseline and every 6 months (or more frequently in higher risk patients) for patients continuing therapy. Also, it is recommended to limit refill quantity to a maximum of 6 months to ensure patients receive essential monitoring. Standard of care to ensure appropriate patient monitoring on DOAC therapy includes ordering necessary labs and performing an assessment by physicians or advance practice providers.

In an effort to improve patient outcomes, access to affordable medications, adherence, and quality of care, the Ambulatory Pharmacy Medication Management Care Clinic (APMMCC) was founded at Novant Health for ambulatory care clinical pharmacist practitioners (CPPs) to fulfill the goal. Currently, patients are referred to the APMMCC team by physicians or advance practice providers to supplement patient’s current disease management. Following referral, ambulatory care CPPs help interested patients become established with Novant Health Home Delivery (NHHD) Pharmacy for cost-savings and complete necessary monitoring and follow-up dependent on therapy. NHHD Pharmacy provides cost savings through the 340B program which allows covered entities to provide federal resources (such as discounted medications) to more eligible patients.

Methods

A retrospective chart review was conducted on patients prescribed DOAC therapy between August 1, 2022, and December 31, 2023, across Novant Health outpatient facilities. The study was approved by the health system’s institutional review board. Patients older than 18 years old and on DOAC therapy for at least 6 months were included in the study. Patients on warfarin or who had a history of thrombophilia were excluded. Patients were matched 1:1 between the groups based on the DOAC prescribed and specific age group (grouped by decades) of the patients.

The primary end point was to compare the percentage of patients who had a CBC lab ordered at 6 months (defined as < 210 days) in the APMMCC group versus the standard of care group. Secondary end points included the percentage of patients on an appropriate DOAC dose (based on specific guidance for each DOAC^4-7), percentage of patients with a completed CBC at 6 months (defined as having a lab result and interpretation), percentage of patients admitted to the hospital for a DOAC-related bleeding event, percentage of patients with 1-year readmission due to cardiovascular indication, and the potential time saved to other providers. Data analysis was conducted utilizing chi-square test and descriptive statistics.

Results

Patient characteristics: A total of 140 patients prescribed DOAC therapy were included, with 70 patients included in each group. The average patient age was similar across both groups (Table 1). The majority of patients were prescribed apixaban to treat NVAF.

Table 1. Baseline Characteristics

Primary end point: The percentage of patients with a CBC ordered within 6 months for APMMCC versus standard care is displayed in Figure 1. Significantly more patients followed by APMMCC had a CBC ordered within 6 months compared with standard care (79% vs 60%; p=0.0172).

Figure 1. CBC Ordered Within 6 Months

Secondary end points: Significantly more patients seen via APMMCC were prescribed an appropriate DOAC dose compared with standard care, as shown in Figure 2 (97% vs 81%; p=0.0026).

Figure 2. Appropriate DOAC Dose Prescribed

The percentage of patients with a CBC completed in 6 months was greater for APMMCC, although there was not a statistically significant difference between groups, as displayed in Figure 3 (71% vs 57%; p=0.0778).

Figure 3. CBC Completed Within 6 Months

No patients were hospitalized in either group for a DOAC-related bleeding event and 1 patient in both groups was hospitalized due to cardiovascular indication for DOAC therapy (Table 2).

Table 2. Hospital admission for DOAC-related bleeding event and 1-year readmission for cardiovascular indication

Assuming other providers’ patient visits are 15 minutes in duration, with 70 completed patient visits via APMMCC, the time saved during the study period to other providers was calculated to be 17.5 hours.

Discussion

Significantly more patients had a CBC ordered in 6 months via APMMCC, showing that CPPs are making the effort to monitor patients according to the health system’s standards. APMMCC prescribed the appropriate DOAC dose to a statistically significant greater percentage of patients compared with standard care, highlighting the benefit CPPs provide to ensure necessary dose adjustments are executed. Though there was not a significant difference seen for CBC completed in 6 months, the result emphasizes patients are monitored and followed similarly in a virtual setting with a CPP as in-person with other providers. The time saved to providers was collected during the study, although the actual time saved for other providers could be more, considering follow-up visits are necessary during treatment.

Limitations

Limitations identified in this study include the retrospective design and reliance on documentation. It also has a small study population, a brief study period (because APMMCC was established August 2022), and potential bias due to multivariate matching for DOAC and decade age of year.

Conclusions

The results of this study emphasize the key role CPPs fulfill to provide an optimal medication regimen by prescribing appropriate doses and monitoring patients according to current standards. Additionally, the study highlights CPPs’ ability to provide similar patient monitoring and follow-up in a virtual setting as in-person. Further studies with longer durations that are inclusive of more patients and multiple instances of patient assessment and follow-up may be necessary to more fully assess the impact of APMMCC. Future directions can include provider education to increase awareness surrounding the health system’s policy and evaluating patient satisfaction with virtual visits. Future efforts for APMMCC include implementation of reminder calls to patients to retrieve their ordered labs within the duration specified by the current policy.

References

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2. Navar AM, Kolkailah AA, Overton R, et al. Trends in Oral Anticoagulant Use Among 436 864 Patients With Atrial Fibrillation in Community Practice, 2011 to 2020. J Am Heart Assoc. 2022;11(22):e026723. Accessed August 23, 2023. doi:10.1161/JAHA.122.026723

3. Tomaselli GF, Mahaffey KW, Cuker A, et al. 2020 ACC Expert Consensus Decision Pathway on Management of Bleeding in Patients on Oral Anticoagulants: A Report of the American College of Cardiology Solution Set Oversight Committee [published correction appears in J Am Coll Cardiol. 2021 Jun 1;77(21):2760]. J Am Coll Cardiol. 2020;76(5):594-622. Accessed August 23, 2023. doi:10.1016/j.jacc.2020.04.053

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