We assessed the predictive accuracy of the Warfarin Pharmacogenetics Consortium (IWPC) algorithm in a prospective cohort of 376 high-risk elderly patients (≥65 years) who required new treatment with warfarin for either medical (non valvular atrial fibrillation) or surgical conditions (heart valve replacement), had ≥1 comorbid conditions, and regularly used ≥2 other drugs. Follow-up visits were performed according to clinical practice and lasted for a maximum of 1 year. Two hundred and eighty-three (75%) patients achieved a stable maintenance dose. Warfarin maintenance doses were low on average (median 20.3 mg/week, interquartile range, 14.1-27.7 mg/week) and were substantially overestimated by the IWPC algorithm. Overall the percentage of patients whose predicted dose of warfarin was within 20% of the actual stable dose was equal to 37.5%, (95% CI 32.0-43.3%). IWPC algorithm explained only 31% of the actual warfarin dose variability. Modifications of the IWPC algorithm are needed in high-risk elderly people.
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http://dx.doi.org/10.1038/s41397-019-0129-6 | DOI Listing |
Pharmacogenet Genomics
December 2024
School of Nursing and Health, Henan University, Kaifeng, China.
Objective: Warfarin has a narrow therapeutic window and large variability in dosing that are affected by clinical and genetic factors. To help guide the dosing of warfarin, the Clinical Pharmacogenetics Implementation Consortium has recommended the use of pharmacogenetic algorithms, such as the ones developed by the International Warfarin Pharmacogenetics Consortium (IWPC) and by Gage et al. when genotype information is available.
View Article and Find Full Text PDFDrug Metab Pers Ther
September 2023
Department of Pharmacology, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India.
Pharm Pract (Granada)
September 2022
PhD, Msc. Department of Pharmacology, Faculty of Pharmacy, University of Gezira, Wad Medani-Sudan.
Background: Warfarin is well known as a narrow therapeutic index that has prodigious variability in response which challenges dosing adjustment for the maintenance of therapeutic international normalized ratio. However, an appreciated population not on new oral anticoagulants may still need to be stabilized with warfarin dosing.
Objective: The current study's main objective was to validate and compare two models of warfarin clinical algorithm models namely the Gage and the International Warfarin Pharmacogenetics Consortium (IWPC) with warfarin 5 mg fixed standard dosing strategy in a sample of Sudanese subjects.
Comput Biol Med
February 2023
Laboratory of Clinical Pharmacology, Division of Cellular & Molecular Research, National Cancer Centre Singapore, Singapore; Singapore Immunology Network, Agency for Science, Technology & Research (A*STAR), Singapore; Centre for Clinician Scientist Development, Duke-NUS Medical School, Singapore. Electronic address:
J Clin Pharmacol
May 2023
Department of Thoracic Surgery, First Affiliated Hospital of Henan University, Kaifeng, China.
Warfarin has a long record of safe and effective clinical use, and it remains one of the most commonly prescribed drugs for the prevention and treatment of thromboembolic conditions even in the era of direct oral anticoagulants. To address its large interindividual variability and narrow therapeutic window, the Clinical Pharmacogenetics Implementation Consortium has recommended using pharmacogenetic dosing algorithms, such as the ones developed by the International Warfarin Pharmacogenetics Consortium (IWPC) and by Gage et al, to dose warfarin when genotype information is available. In China, dosing algorithms based on local patient populations have been developed and evaluated for predictive accuracy of warfarin maintenance doses.
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