The effectiveness of Pharmacist-driven Medication optimization: A Retrospective study on Warfarin and Digoxin

ABSTRACT

Background: Warfarin and digoxin are essential for managing cardiovascular conditions but carry risks of adverse drug reactions (ADRs) due to their narrow therapeutic indices, particularly in patients on concurrent therapy, with polypharmacy, or chronic kidney disease (CKD). The role of clinical pharmacists in optimizing these therapies remains underexplored. Objective: To evaluate the impact of pharmacist-driven interventions on therapeutic success, ADRs, medication adherence, and hospital readmissions in patients on warfarin, digoxin, or both. Methods: This retrospective cohort study analyzed 270 patients at a tertiary care hospital in Amman, Amman, Jordan, from January to December 2023. Outcomes included therapeutic success, time to therapeutic target and stabilization, ADR incidence, adherence, and hospital readmissions. Data were analyzed using Kaplan-Meier survival analysis, Cox proportional hazards models, and multivariate logistic regression. Results: Of 270 patients (162 warfarin-only, 80 digoxin-only, 28 concurrent), pharmacists delivered 277 interventions (1.03/patient), achieving therapeutic success in 83.7% (226/270). Warfarin-only patients reached therapeutic INR in 88.2% within 8.2 ± 11 days, digoxin-only in 86.3% within 11 ± 13 days, and concurrent therapy in 85.7% (INR) and 71.4% (digoxin) within 9.1 ± 9 and 14 ± 11 days, stabilizing at 26–33 days. Frequent interventions (HR=1.61–1.92, p<0.001–0.014) reduced stabilization time by 7–12 days. Interventions tripled success odds (OR=2.87, p<0.001), prevented 18 ADRs (reducing the rate from 20.4% to 13.7%), and improved adherence odds (OR=1.73, p=0.07), increasing PDC by 6–12%. Polypharmacy (OR=1.89, p=0.02), CKD (OR=3.21, p=0.003), and concurrent therapy (OR=2.13, p=0.04) increased ADR risk, while polypharmacy reduced adherence (OR=0.58, p=0.02). Readmissions (38 events, 14.1% event rate) were reduced from 17.0% by preventing 8 events, though the concurrent subgroup had a 35.7% rate. Conclusions: Pharmacist-driven interventions significantly enhance therapeutic success, reduce ADRs, improve adherence, and lower readmissions in warfarin and digoxin therapy, particularly in high-risk patients, supporting their integration into cardiovascular care teams.

KEYWORDS

• Warfarin
• Digoxin
• Clinical Pharmacists
• Polypharmacy
• Chronic Kidney Disease
• Medication Adherence
• Therapeutic Drug Monitoring
• Hospital Readmissions

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• DOI10.18549/PharmPract.2025.4.3360Copy

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