Study Design: To assess whether warfarin dose requirement, anticoagulation control, and risk of hemorrhage differ in kidney transplant recipients (KTRs) compared with patients without kidney transplants (non-KTRs). Design: Analysis of data from the Warfarin Pharmacogenetics Cohort, a prospective cohort of first-time warfarin users followed at two anticoagulation clinics. Setting: Two outpatient anticoagulation clinics at two large, academic, tertiary care hospitals. Patients: Adults aged 20 years or older starting warfarin for anticoagulation with a therapeutic international normalized ratio (INR) goal of 2–3 who were KTRs (n=65) or non-KTRs (n=1630). Measurements and Main Results: Warfarin dose requirement, anticoagulation control, and risk of hemorrhage were assessed in each group. KTRs required an approximately 20% lower warfarin dose (4.7 vs 5.6 mg/day, p=0.0005) compared with non-KTRs. Genetic variants had similar effects on dose in both groups. Mean percentage of time in therapeutic range (PTTR) was similar among KTRs and non-KTRs. Although the proportion of patients achieving good anticoagulation control (PTTR ≥ 60%) was low in both groups, it was similar among KTRs and non-KTRs. KTRs had a higher risk of major hemorrhage (hazard ratio 2.1, p=0.0081), but this difference was not statistically significant after controlling for kidney function, clinical, and genetic factors. Conclusion: KTRs initiating warfarin require lower doses and closer monitoring to optimize anticoagulation therapy. Additional studies are needed to confirm these findings.
Bibliographical noteFunding Information:
The first two authors contributed equally. This work was supported in part by grants from the National Heart Lung and Blood Institute (RO1HL092173, 1K24HL133373), the National Institutes of Health Clinical and Translational Science Award Program (UL1 TR000165), and the National Institute of Diabetes and Digestive and Kidney Diseases (5T32DK007545-27). *Address for correspondence: Nita A. Limdi, Department of Neurology, University of Alabama at Birmingham, 1235 Jefferson Tower, 625 19th Street South, Birmingham, AL 35294-0021; e-mail: email@example.com. © 2017 Pharmacotherapy Publications, Inc.
© 2017 Pharmacotherapy Publications, Inc.
- kidney transplant