Inpatient pharmacy‐driven antithrombosis stewardship efforts on warfarin to direct oral anticoagulant conversions

Background Over 6 million people in the United States require anticoagulation. Current guidelines recommend direct oral anticoagulants (DOACs) over warfarin for select indications due to increased safety and similar efficacy. However, data suggest warfarin to DOAC conversion occurs in less than 5% of patients. Objectives To assess rates of conversion from warfarin to DOACs and the rate of inpatient pharmacist assessment for warfarin to DOAC conversions using an evidence‐based DOAC checklist. Methods In this retrospective cohort study, all patients ≥18 years old admitted on warfarin from January 1, 2018 to February 28, 2020 were identified via query of the electronic health record (EHR). Patients were excluded if discharged to hospice or if anticoagulation was permanently discontinued. In January 2019, an evidence‐based checklist was developed by the inpatient antithrombosis stewardship team and embedded into an EHR‐based standardized clinical documentation form prompting pharmacist assessment for DOAC therapy. Autoregressive integrated moving average (ARIMA) models were utilized to compare pre‐ and post‐implementation rates of pharmacist‐driven evaluation for warfarin to DOAC switch along with actual conversion rates. Additional outcomes were documented reasons for not switching and proportion of newly‐switched patients referred to our antithrombosis clinic. Results Ultimately, 538 inpatient encounters were included (237 pre‐implementation of the DOAC eligibility checklist; 301 post‐implementation). Warfarin to DOAC conversions increased from a mean of 1.08 patients/month pre‐implementation of the DOAC eligibility checklist to 3.62 patients/month post‐implementation ( p < 0.0001). Likewise, pharmacist evaluation for switch increased significantly from a mean of 2.00 patients/month pre‐implementation of the DOAC eligibility checklist to 17.69 patients/month post‐implementation ( p < 0.0001). In addition, referrals to the anticoagulation clinic significantly increased from a mean of 1.08–4.08 patients/month ( p < 0.0001). Conclusion Use of an evidence‐based checklist embedded into the inpatient EHR increased warfarin to DOAC conversions and supported overall antithrombosis stewardship efforts. Conversion rates remained fairly low. Further opportunity exists to optimize patient safety and health systems savings with ongoing stewardship efforts.