Category: Federal Forum Posters
Purpose: Direct oral anticoagulant (DOAC) is an alternative to vitamin K antagonist warfarin in the treatment for non-valvular atrial fibrillation (NVAF) and venous thromboembolism (VTE). Unlike warfarin, DOAC use is not limited by diet restriction, offers fewer drug interactions, and requires less clinic visits. The purpose of this study is to demonstrate that there is no significant difference in clinical outcomes when converting from warfarin to DOAC.
Methods: The institutional review board approved this retrospective chart review study. Patients were enrolled if they have a diagnosis of NVAF or VTE and were on warfarin and switched to DOAC. Patients taking an anticoagulant for indications other than NVAF or VTE and had less than 6 months of treatment with either warfarin or DOAC were excluded. The study index date was the conversion from warfarin to DOAC date with the study period defined as 6 months before and after the index date. Collected baseline data were: indication, anticoagulant and dose, concurrent aspirin use, concurrent thienopyridine use, serum creatinine (Scr), hemoglobin/hematocrit (H/H), alanine aminotransferase (ALT), weight, and age. During the study period, collected data included: number of clinic visits (face-to-face and telephone visits); interventions made by pharmacists; reasons for stopping DOAC (if appropriate); alternative anticoagulant used after stopping DOAC; significant bleeding event. We aimed to assess the tolerability to DOAC after conversion and to evaluate the reasons for stopping DOAC, if occurred. We also evaluated clinic utilization and pharmacist interventions made. Description statistics were used to assess baseline characteristics, adverse events, and pharmacist interventions. T-test was used to compare number of clinic visits before and after the conversion.
Results: One hundred sixty-three patients met the inclusion and exclusion criteria and were included in the analysis. Overall, 7.3 percent (n equals 12) patients experienced adverse events including bleeding, falls, acute kidney injury, and severe back pain. Among the cohorts converted to the different DOACs, dabigatran converters experienced the highest adverse event, followed by rivaroxaban and apixaban at 10 percent, 6.8 percent and 6.3 percent, respectively. For the study cohort, 9.8 percent (n equals 16) of patients stopped taking DOAC due to bleeding, decreased H/H, increased Scr, or increased ALT. Of which 6.1 percent (n equals 10) switched back to warfarin due to bleeding, drug-drug interaction, hepatitis, or starting hemodialysis, and 3.7 percent (n equals 6) switched to another DOAC due to patient request for a reversal agent, worsening renal function, or switched initiated by another provider. Clinic utilization decreased following DOAC conversion with follow-up appointments changed from average 7.8 to 4.3 visits, which was shown to be statistically significant (p less than 0.001). Pharmacists interventions accounted for 18.4 percent (n equals 30) with most alerting primary care providers with significant changes in laboratory values.
Conclusion: DOACs are safe and effective alternative to warfarin in the treatment of NVAF and VTE in appropriate patients. Our data suggested the conversion from warfarin to DOAC is well tolerated with a low rate of reversion back to warfarin therapy. Anticoagulation clinic pharmacist providers effectively managed and monitored patients on DOACs after the conversion. Clinic utilization decreased which led to reducing pharmacist staff. This study may help other healthcare institutions to initiate a warfarin to DOAC conversion with proper monitoring by pharmacists in those diagnosed with NVAF or VTE.
Tiffany Luong– Pharmacist, Veterans Affair Long Beach, Milpitas, CA