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Age-stratified outcome of a genotype-guided dosing algorithm for acenocoumarol and phenprocoumon.
Zhang, Y, de Boer, A, Verhoef, TI, van der Meer, FJ, Le Cessie, S, Manolopoulos, VG, Maitland-van der Zee, AH, ,
Journal of thrombosis and haemostasis : JTH. 2017;(3):454-464
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Abstract
UNLABELLED Essentials The EU-PACT trial was used to investigate age on the interaction between coumarins and genotype. The results support the use of genotype-guided dosing for phenprocoumon in patients < 75 years. For patients ≥ 75 years the phenprocoumon algorithm should be revised and further tested. No influence of comorbidities and co-current drug use was found that could explain the differences. SUMMARY Background Age seemed to affect the interaction between coumarins and genotype in the acenocoumarol and phenprocoumon arm of the European Pharmacogenetics of Anticoagulant Therapy (EU-PACT) trial. Objectives To investigate the effect of genotype-guided dosing stratified by age and the potential factors causing a difference. Patients/Methods Data from the acenocoumarol/phenprocoumon arm of the EU-PACT trial were used. The percentages of time below the therapeutic range, time above the therapeutic range and time in the therapeutic range (TTR) during the initial 12 weeks of therapy were compared between the genotype-guided group and the control group among younger (< 75 years) and older (≥ 75 years) patients by the use of independent t-tests, and adjusted for sex, height, weight and co-medications by the use of linear regression. Results Among younger phenprocoumon users, TTR during the first 12 weeks in the genotype-guided group (n = 55) was 9.5% (95% confidence interval [CI] 1.3 to 17.8) higher than in the control group (n = 63), with a remarkably lower percentage of time above this range (difference: - 9.6%, 95% CI - 19.0 to - 0.2) and a similar time below this range. Older patients dosed by the genotype-guided algorithm (n = 24) spent more time above the range (difference: 27.5%, 95% CI 12.9 to 42.0). For acenocoumarol users, there were no significant differences between the genotype-guided and control groups for most outcomes, except for a lower percentage of time below the range among older patients. Conclusions The genotype-guided algorithm for phenprocoumon in the EU-PACT trial benefitted younger patients more, but for older patients the algorithm needs to be revised and tested in further research.
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Estimation of the warfarin dose with a pharmacogenetic refinement algorithm in Chinese patients mainly under low-intensity warfarin anticoagulation.
Xu, Q, Xu, B, Zhang, Y, Yang, J, Gao, L, Zhang, Y, Wang, H, Lu, C, Zhao, Y, Yin, T
Thrombosis and haemostasis. 2012;(6):1132-40
Abstract
Pharmacogenetic (PG) dosing algorithms have been confirmed to predict warfarin therapeutic dose more accurately; however, most of them are based on standard intensity of warfarin anticoagulation, and their utility outside this range is limited. This study was designed to develop and validate a PG refinement algorithm in Chinese patients mainly under low-intensity warfarin anticoagulation. Consented Chinese-Han patients (n=310) under stable warfarin treatment were randomly divided into a derivation (n=207) and a validation cohort (n=103), with 83% and 80% of the patients under low-intensity anticoagulation, respectively. In the derivation cohort, a PG algorithm was constructed on the basis of genotypes (CYP2C9*3 and VKORC1-1639A/G) and clinical data. After integrating additional covariates of international normalised ratio (INR) values (INR on day 4 of therapy and target INR) and genotype of CYP4F2 (rs2108622), a PG refinement algorithm was established and explained 54% of warfarin dose variability. In the validation cohort, warfarin dose prediction was more accurate (p < 0.01) with the PG refinement algorithm than with the PG algorithm and the fixed dose approach (3 mg/day). In the entire cohort, the PG refinement algorithm could accurately identify larger proportions of patients with lower dose requirement (≤2 mg/day) and higher dose requirement (≥4 mg/day) than did the PG algorithm. In conclusion, PG refinement algorithm integrating early INR response and three genotypes (CYP2C9*3, VKORC1-1639A/G, CYP4F2 rs2108622) improves the accuracy of warfarin dose prediction in Chinese patients mainly under low-intensity anticoagulation.