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Warfarin is a highly prescribed anticoagulant used across the globe. The two enzymes responsible for the metabolism of warfarin in the liver according to the steps above are CYP2C9 and VKORC1. Both enzymes are found to have genetic polymorphisms which can impact the effect of warfarin therapy on coagulation.
Hospitalized patients identified as those needing warfarin treatment were subjected to Warfarin GenoSTAT genetic testing performed by Iverson Genetics, to screen for the presence of polymorphisms in the CYP2C9 and VKORC1 enzymes. Dosing was then prescribed according to the results of the genetic test in conjunction with warfarindosing.org. The control group for the first part of the study was the group of patients completely lacking polymorphisms of the CYP2C9 and VKORC1 enzymes. Study group one was the group of patients who had polymorphisms of the CYP2C9 enzyme only. Study group two was the group of patients who had polymorphisms of the VKORC1 enzyme only. Study group three was the group of patients who had polymorphisms of both the CYP2C9 and VKORC1 enzymes.
Therapeutic INR was reached by the control group after an average of 100.11 ± 81.90 hours. Study group one achieved therapeutic INR after an average of 58.61 ± 29.84 hours (P=0.00668). Study group two achieved therapeutic INR after an average of 93.6 ± 41.85 hours (P=0.865). Study group three achieved therapeutic INR after an average of 49.92 ± 23.53 hours (P=0.0376). According to previous studies, the national average to reach a therapeutic INR is 168.36 ± 73.44 hours for patients not receiving genetic testing before dosing [8,9]. The average time to reach therapeutic INR in a pharmacist-managed group was 93.6 hours. The data collected in this study shows an average time of only 73.21 ± 56.517 hours until therapeutic INR was achieved.
Inconsistency in the response to warfarin is complex; it includes genetic polymorphisms in CYP2C9, VKORC1, and possibly other influences still being researched. Genetically customized warfarin doses provide an appealing replacement to the “average” effective dose method.
Poster Sessions, Expo North
Sunday, March 10, 2013, 9:45 a.m.-10:30 a.m.
Session Title: Improving Cardiovascular Health Services
Abstract Category: 28. Quality of Care and Outcomes Assessment
Presentation Number: 1201-113
- 2013 American College of Cardiology Foundation