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Asiimwe IG, Pirmohamed M. Ethnic Diversity and Warfarin Pharmacogenomics. Front Pharmacol 2022; 13:866058. [PMID: 35444556 PMCID: PMC9014219 DOI: 10.3389/fphar.2022.866058] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 03/14/2022] [Indexed: 12/23/2022] Open
Abstract
Warfarin has remained the most commonly prescribed vitamin K oral anticoagulant worldwide since its approval in 1954. Dosing challenges including having a narrow therapeutic window and a wide interpatient variability in dosing requirements have contributed to making it the most studied drug in terms of genotype-phenotype relationships. However, most of these studies have been conducted in Whites or Asians which means the current pharmacogenomics evidence-base does not reflect ethnic diversity. Due to differences in minor allele frequencies of key genetic variants, studies conducted in Whites/Asians may not be applicable to underrepresented populations such as Blacks, Hispanics/Latinos, American Indians/Alaska Natives and Native Hawaiians/other Pacific Islanders. This may exacerbate health inequalities when Whites/Asians have better anticoagulation profiles due to the existence of validated pharmacogenomic dosing algorithms which fail to perform similarly in the underrepresented populations. To examine the extent to which individual races/ethnicities are represented in the existing body of pharmacogenomic evidence, we review evidence pertaining to published pharmacogenomic dosing algorithms, including clinical utility studies, cost-effectiveness studies and clinical implementation guidelines that have been published in the warfarin field.
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Affiliation(s)
- Innocent G Asiimwe
- The Wolfson Centre for Personalized Medicine, MRC Centre for Drug Safety Science, Department of Pharmacology and Therapeutics, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Munir Pirmohamed
- The Wolfson Centre for Personalized Medicine, MRC Centre for Drug Safety Science, Department of Pharmacology and Therapeutics, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, United Kingdom
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Lindley KJ, Limdi NA, Cavallari LH, Perera MA, Lenzini P, Johnson JA, Wu AHB, Ridker PM, King C, Eby CS, Patel S, Shah SV, Mark Beasley T, Li J, Gage BF. Warfarin Dosing in Patients with CYP2C9*5 Variant Alleles. Clin Pharmacol Ther 2022; 111:950-955. [PMID: 35108398 DOI: 10.1002/cpt.2549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 01/27/2022] [Indexed: 11/06/2022]
Abstract
Pharmacogenetic dosing improves the accuracy of warfarin dosing, but current pharmacogenetic dosing algorithms are less accurate in populations of African ancestry. The cytochrome P450 2C9*5 (CYP2C9*5) allele is found almost exclusively in populations of African ancestry, and in-vitro studies suggest CYP2C9*5 is associated with reduced clearance of warfarin. The clinical relevance of this SNP is uncertain. In this multi-centered study of 2298 patients (49% female, 35% Black) taking warfarin, we quantified the association between the CYP2C9*5 allele and warfarin requirements. The CYP2C9*5 SNP was present in 2.3% of Black and 0.07% of White patients. Without taking CYP2C9*5 into account, pharmacogenetic algorithms that include other SNPs overestimated the warfarin dose by 30% (95% CI [19%-40%], p<0.001), an average of 1.87 mg/d (SD 1.64) in heterozygotes (p < 0.001). Non-carriers required a slightly (0.23 mg/d, SD 2.09) higher than predicted dose. Genotyping for CYP2C9*5 corrected the potential overdose and halved overall dosing error in heterozygotes. Patients carrying CYP2C9*5 require a clinically relevant reduction in warfarin dose. Given the potential to improve the accuracy and safety of warfarin dosing in populations of African ancestry, we have incorporated this SNP into a non-profit website to assist warfarin initiation (www.WarfarinDosing.org).
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Affiliation(s)
| | | | | | | | | | | | | | - Paul M Ridker
- Brigham and Women's Hospital, Harvard Medical School
| | | | | | | | | | | | - Juan Li
- Washington University, School of Medicine
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Gage BF, Bass AR, Lin H, Woller SC, Stevens SM, Al-Hammadi N, Anderson JL, Li J, Rodriguez T, Miller JP, McMillin GA, Pendleton RC, Jaffer AK, King CR, Whipple B, Porche-Sorbet R, Napoli L, Merritt K, Thompson AM, Hyun G, Hollomon W, Barrack RL, Nunley RM, Moskowitz G, Dávila-Román V, Eby CS. Effect of Low-Intensity vs Standard-Intensity Warfarin Prophylaxis on Venous Thromboembolism or Death Among Patients Undergoing Hip or Knee Arthroplasty: A Randomized Clinical Trial. JAMA 2019; 322:834-842. [PMID: 31479138 PMCID: PMC6724181 DOI: 10.1001/jama.2019.12085] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
IMPORTANCE The optimal international normalized ratio (INR) to prevent venous thromboembolism (VTE) in warfarin-treated patients with recent arthroplasty is unknown. OBJECTIVE To determine the safety and efficacy of a target INR of 1.8 vs 2.5 for VTE prophylaxis after orthopedic surgery. DESIGN, SETTING, AND PARTICIPANTS The randomized Genetic Informatics Trial (GIFT) of Warfarin to Prevent Deep Vein Thrombosis enrolled 1650 patients aged 65 years or older initiating warfarin for elective hip or knee arthroplasty at 6 US medical centers. Enrollment began in April 2011 and follow-up concluded in October 2016. INTERVENTIONS In a 2 × 2 factorial design, participants were randomized to a target INR of 1.8 (n = 823) or 2.5 (n = 827) and to either genotype-guided or clinically guided warfarin dosing. For the first 11 days of therapy, open-label warfarin dosing was guided by a web application. MAIN OUTCOMES AND MEASURES The primary outcome was the composite of VTE (within 60 days) or death (within 30 days). Participants underwent screening duplex ultrasound postoperatively. The hypothesis was that an INR target of 1.8 would be noninferior to an INR target of 2.5, using a noninferiority margin of 3% for the absolute risk of VTE. Secondary end points were bleeding and INR values of 4 or more. RESULTS Among 1650 patients who were randomized (mean age, 72.1 years; 1049 women [63.6%]; 1502 white [91.0%]), 1597 (96.8%) received at least 1 dose of warfarin and were included in the primary analysis. The rate of the primary composite outcome of VTE or death was 5.1% (41 of 804) in the low-intensity-warfarin group (INR target, 1.8) vs 3.8% (30 of 793) in the standard-treatment-warfarin group (INR target, 2.5), for a difference of 1.3% (1-sided 95% CI, -∞ to 3.05%, P = .06 for noninferiority). Major bleeding occurred in 0.4% of patients in the low-intensity group and 0.9% of patients in the standard-intensity group, for a difference of -0.5% (95% CI, -1.6% to 0.4%). The INR values of 4 or more occurred in 4.5% of patients in the low-intensity group and 12.2% of the standard-intensity group, for a difference of -7.8% (95% CI, -10.5% to -5.1%). CONCLUSIONS AND RELEVANCE Among older patients undergoing hip or knee arthroplasty and receiving warfarin prophylaxis, an international normalized ratio goal of 1.8 compared with 2.5 did not meet the criterion for noninferiority for risk of the composite outcome of VTE or death. However, the trial may have been underpowered to meet this criterion and further research may be warranted. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT01006733.
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Affiliation(s)
- Brian F. Gage
- Department of Medicine, Washington University in St Louis, St Louis, Missouri
| | - Anne R. Bass
- Department of Medicine, Hospital for Special Surgery, New York, New York
| | - Hannah Lin
- Department of Medicine, Washington University in St Louis, St Louis, Missouri
- Department of Medical Education, University of Massachusetts, Worcester
| | - Scott C. Woller
- Department of Medicine, Intermountain Medical Center, Salt Lake City, Utah
- Department of Medicine, University of Utah, Salt Lake City
| | - Scott M. Stevens
- Department of Medicine, Intermountain Medical Center, Salt Lake City, Utah
- Department of Medicine, University of Utah, Salt Lake City
| | - Noor Al-Hammadi
- Department of Medicine, Washington University in St Louis, St Louis, Missouri
| | - Jeffrey L. Anderson
- Department of Medicine, University of Utah, Salt Lake City
- Department of Cardiology, Intermountain Medical Center, Salt Lake City, Utah
| | - Juan Li
- Department of Medicine, Washington University in St Louis, St Louis, Missouri
| | - Tomás Rodriguez
- Department of Medicine, Washington University in St Louis, St Louis, Missouri
| | - J. Philip Miller
- Department of Medicine, Washington University in St Louis, St Louis, Missouri
| | | | | | - Amir K. Jaffer
- Department of Medicine, New York Presbyterian Queens Hospital, New York
| | - Cristi R. King
- Department of Medicine, Washington University in St Louis, St Louis, Missouri
| | - Brandi Whipple
- Department of Medicine, Washington University in St Louis, St Louis, Missouri
| | | | - Lynnae Napoli
- Department of Medicine, University of Utah, Salt Lake City
| | - Kerri Merritt
- Department of Medicine, Hospital for Special Surgery, New York, New York
| | - Anna M. Thompson
- Department of Medicine, Washington University in St Louis, St Louis, Missouri
- Department of Medical Education, University of Central Florida College of Medicine, Orlando
| | - Gina Hyun
- Department of Medicine, Washington University in St Louis, St Louis, Missouri
- Department of Radiology, Walter Reed National Military Medical Center, Bethesda, Maryland
| | - Wesley Hollomon
- Department of Orthopedic Surgery, Hospital for Special Surgery, New York, New York
| | - Robert L. Barrack
- Department of Orthopedic Surgery, Washington University in St Louis, St Louis, Missouri
| | - Ryan M. Nunley
- Department of Orthopedic Surgery, Washington University in St Louis, St Louis, Missouri
| | - Gerard Moskowitz
- Department of Medicine, Washington University in St Louis, St Louis, Missouri
| | - Victor Dávila-Román
- Department of Medicine, Washington University in St Louis, St Louis, Missouri
| | - Charles S. Eby
- Department of Medicine, Washington University in St Louis, St Louis, Missouri
- Department of Pathology and Immunology, Washington University in St Louis, St Louis, Missouri
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Tan-Koi WC, Limenta M, Mohamed EHM, Lee EJD. The Importance of Ethnicity Definitions and Pharmacogenomics in Ethnobridging and Pharmacovigilance. Pharmacogenomics 2019. [DOI: 10.1016/b978-0-12-812626-4.00011-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Shendre A, Dillon C, Limdi NA. Pharmacogenetics of warfarin dosing in patients of African and European ancestry. Pharmacogenomics 2018; 19:1357-1371. [PMID: 30345882 PMCID: PMC6562764 DOI: 10.2217/pgs-2018-0146] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 09/28/2018] [Indexed: 12/20/2022] Open
Abstract
Despite the introduction of direct acting oral anticoagulants, warfarin remains the most commonly prescribed oral anticoagulant. However, warfarin therapy is plagued by the large inter- and intrapatient variability. The variability in dosing fueled research to identify clinical and genetic predictors and develop more accurate dosing algorithms. Observational studies have demonstrated the significant impact of single nucleotide polymorphisms in CYP2C9 and VKORC1 on warfarin dose in patients of European ancestry and African-Americans. This evidence supported the design and conduct of clinical trials to assess whether genotype-guided dosing results in improved anticoagulation control and outcomes. The trial results have shown discordance by race, with pharmacogenetic algorithms improving dose and anticoagulation control among European ancestry patients compared with African-American patients. Herein, we review the evidence from observational and interventional studies, highlight the need for inclusion of minority race groups and propose the need to develop race specific dosing algorithms.
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Affiliation(s)
- Aditi Shendre
- Department of Epidemiology, Richard M Fairbanks School of Public Health, Indiana University Purdue University Indianapolis, IN 46202, USA
| | - Chrisly Dillon
- Department of Neurology, School of Medicine, University of Alabama at Birmingham, AL 35294, USA
| | - Nita A Limdi
- Department of Neurology, School of Medicine, University of Alabama at Birmingham, AL 35294, USA
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Yang J, Gao L, Zhang Y, Wang H, Lu C, Zhao Y, Xu Q, Xu B, Zhang Y, Yin T. Estimation of the warfarin dose with a pharmacogenetic refinement algorithm in Chinese patients mainly under low-intensity warfarin anticoagulation. Thromb Haemost 2017; 108:1132-40. [DOI: 10.1160/th12-05-0362] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 08/14/2012] [Indexed: 12/28/2022]
Abstract
SummaryPharmacogenetic (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.
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Janzic A, Locatelli I, Kos M. The Value of Evidence in the Decision-Making Process for Reimbursement of Pharmacogenetic Dosing of Warfarin. Am J Cardiovasc Drugs 2017; 17:399-408. [PMID: 28528365 DOI: 10.1007/s40256-017-0233-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND After early clinical trials that evaluated pharmacogenetic (PG) algorithms, many healthcare payers were reluctant to cover this technology and, consequently, PG dosing of warfarin could not be translated into clinical practice. OBJECTIVE The aim of this study was to estimate the value of upgrading evidence relating to PG dosing of warfarin from the healthcare payer perspective. METHODS Randomized controlled trials (RCTs) that evaluated PG dosing of warfarin were identified through a systematic literature search, and their findings were combined by a cumulative meta-analysis. A health economic model was used to estimate economic outcomes and to calculate the expected value of perfect information (EVPI) as a measure of the value of clinical trials for decision makers. RESULTS Nine RCTs were identified and included in our analysis. The estimated difference in the percentage of time in the therapeutic range was 5.6 percentage points in 2007, decreasing to 4.3 percentage points when all studies were included. At a reimbursement price of €160 per PG testing, the EVPI for the clinical benefit was estimated at €80 and €90 per patient in 2007 and 2014, respectively. A reduction in the price of PG testing to €40, which was observed in this period, resulted in an EVPI of €3 per patient. CONCLUSIONS The estimated cumulative effect of PG dosing has remained similar since 2007, but additional evidence has contributed to a more precise estimation. While these variations should not affect the reimbursement decision, a large decline in the cost of PG testing in recent years calls for reconsideration.
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Affiliation(s)
- Andrej Janzic
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva cesta 7, 1000, Ljubljana, Slovenia.
| | - Igor Locatelli
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva cesta 7, 1000, Ljubljana, Slovenia
| | - Mitja Kos
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva cesta 7, 1000, Ljubljana, Slovenia
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Gage BF, Bass AR, Lin H, Woller SC, Stevens SM, Al-Hammadi N, Li J, Rodríguez T, Miller JP, McMillin GA, Pendleton RC, Jaffer AK, King CR, Whipple BD, Porche-Sorbet R, Napoli L, Merritt K, Thompson AM, Hyun G, Anderson JL, Hollomon W, Barrack RL, Nunley RM, Moskowitz G, Dávila-Román V, Eby CS. Effect of Genotype-Guided Warfarin Dosing on Clinical Events and Anticoagulation Control Among Patients Undergoing Hip or Knee Arthroplasty: The GIFT Randomized Clinical Trial. JAMA 2017; 318:1115-1124. [PMID: 28973620 PMCID: PMC5818817 DOI: 10.1001/jama.2017.11469] [Citation(s) in RCA: 169] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
IMPORTANCE Warfarin use accounts for more medication-related emergency department visits among older patients than any other drug. Whether genotype-guided warfarin dosing can prevent these adverse events is unknown. OBJECTIVE To determine whether genotype-guided dosing improves the safety of warfarin initiation. DESIGN, SETTING, AND PATIENTS The randomized clinical Genetic Informatics Trial (GIFT) of Warfarin to Prevent Deep Vein Thrombosis included patients aged 65 years or older initiating warfarin for elective hip or knee arthroplasty and was conducted at 6 US medical centers. Enrollment began in April 2011 and follow-up concluded in October 2016. INTERVENTIONS Patients were genotyped for the following polymorphisms: VKORC1-1639G>A, CYP2C9*2, CYP2C9*3, and CYP4F2 V433M. In a 2 × 2 factorial design, patients were randomized to genotype-guided (n = 831) or clinically guided (n = 819) warfarin dosing on days 1 through 11 of therapy and to a target international normalized ratio (INR) of either 1.8 or 2.5. The recommended doses of warfarin were open label, but the patients and clinicians were blinded to study group assignment. MAIN OUTCOMES AND MEASURES The primary end point was the composite of major bleeding, INR of 4 or greater, venous thromboembolism, or death. Patients underwent a screening lower-extremity duplex ultrasound approximately 1 month after arthroplasty. RESULTS Among 1650 randomized patients (mean age, 72.1 years [SD, 5.4 years]; 63.6% women; 91.0% white), 1597 (96.8%) received at least 1 dose of warfarin therapy and completed the trial (n = 808 in genotype-guided group vs n = 789 in clinically guided group). A total of 87 patients (10.8%) in the genotype-guided group vs 116 patients (14.7%) in the clinically guided warfarin dosing group met at least 1 of the end points (absolute difference, 3.9% [95% CI, 0.7%-7.2%], P = .02; relative rate [RR], 0.73 [95% CI, 0.56-0.95]). The numbers of individual events in the genotype-guided group vs the clinically guided group were 2 vs 8 for major bleeding (RR, 0.24; 95% CI, 0.05-1.15), 56 vs 77 for INR of 4 or greater (RR, 0.71; 95% CI, 0.51-0.99), 33 vs 38 for venous thromboembolism (RR, 0.85; 95% CI, 0.54-1.34), and there were no deaths. CONCLUSIONS AND RELEVANCE Among patients undergoing elective hip or knee arthroplasty and treated with perioperative warfarin, genotype-guided warfarin dosing, compared with clinically guided dosing, reduced the combined risk of major bleeding, INR of 4 or greater, venous thromboembolism, or death. Further research is needed to determine the cost-effectiveness of personalized warfarin dosing. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01006733.
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Affiliation(s)
- Brian F. Gage
- Washington University in St Louis, St Louis, Missouri
| | - Anne R. Bass
- Hospital for Special Surgery, New York, New York
| | - Hannah Lin
- Washington University in St Louis, St Louis, Missouri
- University of Massachusetts, Worcester
| | - Scott C. Woller
- Intermountain Healthcare, Salt Lake City, Utah
- University of Utah, Salt Lake City
| | - Scott M. Stevens
- Intermountain Healthcare, Salt Lake City, Utah
- University of Utah, Salt Lake City
| | | | - Juan Li
- Washington University in St Louis, St Louis, Missouri
| | | | | | | | | | - Amir K. Jaffer
- New York Presbyterian Queens Hospital, New York, New York
| | | | | | | | | | | | - Anna M. Thompson
- Washington University in St Louis, St Louis, Missouri
- University of Central Florida College of Medicine, Orlando
| | - Gina Hyun
- Washington University in St Louis, St Louis, Missouri
- Saint Louis University, St Louis, Missouri
| | - Jeffrey L. Anderson
- Intermountain Healthcare, Salt Lake City, Utah
- University of Utah, Salt Lake City
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Lesko LJ, Offman E, Brew CT, Garza D, Benton W, Mayo MR, Romero A, Du Mond C, Weir MR. Evaluation of the Potential for Drug Interactions With Patiromer in Healthy Volunteers. J Cardiovasc Pharmacol Ther 2017; 22:434-446. [PMID: 28585859 PMCID: PMC5555446 DOI: 10.1177/1074248417691135] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 12/22/2016] [Indexed: 12/18/2022]
Abstract
INTRODUCTION Patiromer is a potassium-binding polymer that is not systemically absorbed; however, it may bind coadministered oral drugs in the gastrointestinal tract, potentially reducing their absorption. METHODS Twelve randomized, open-label, 3-period, 3-sequence crossover studies were conducted in healthy volunteers to evaluate the effect of patiromer (perpetrator drug) on absorption and single-dose pharmacokinetics (PK) of drugs (victims) that might be commonly used with patiromer. Subjects received victim drug alone, victim drug administered together with patiromer 25.2 g (highest approved dose), and victim drug administered 3 hours before patiromer 25.2 g. The primary PK endpoints were area under the curve (AUC), extrapolated to infinity (AUC0-∞), and maximum concentration ( Cmax). Results were reported as 90% confidence intervals (CIs) about the geometric mean AUC0-∞ and Cmax ratios with prespecified equivalence limits of 80% to 125%. RESULTS Overall, 370 subjects were enrolled, with 365 receiving ≥1 dose of patiromer; 351 subjects completed the studies and all required treatments. When coadministered with patiromer, the 90% CIs for AUC0-∞ remained within 80% to 125% for 9 drugs (amlodipine, cinacalcet, clopidogrel, furosemide, lithium, metoprolol, trimethoprim, verapamil, and warfarin). The AUC0-∞ point estimate ratios for levothyroxine and metformin with patiromer coadministration were ≥80%, with the lower bounds of the 90% CIs at 76.8% and 72.8%, respectively. For ciprofloxacin, the point estimate for AUC0-∞ was 71.5% (90% CI: 65.3-78.4). For 8 of 12 drugs, point estimates for Cmax were ≥80% with patiromer coadministration; for ciprofloxacin, clopidogrel, metformin, and metoprolol, the point estimates were <80%. When patiromer was administered 3 hours after each victim drug, the 90% CIs for AUC0-∞ and Cmax for each drug were within the prespecified 80% to 125% limits. CONCLUSION For 9 of the 12 drugs coadministered with patiromer, there were no clinically significant drug-drug interactions. For 3 drugs (ciprofloxacin, levothyroxine, and metformin), a 3-hour separation between patiromer and their administration resulted in no clinically significant drug-drug interactions.
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Affiliation(s)
- Lawrence J Lesko
- 1 Center for Pharmacometrics and Systems Pharmacology, University of Florida College of Pharmacy, Orlando, FL, USA
| | - Elliot Offman
- 2 Clinical Pharmacology and Pharmacometrics, Celerion, Montreal, Quebec, Canada
| | | | - Dahlia Garza
- 4 Clinical Development, Relypsa, Inc, Redwood City, CA, USA
| | - Wade Benton
- 5 Consultant, Relypsa, Inc, Redwood City, CA, USA
| | - Martha R Mayo
- 4 Clinical Development, Relypsa, Inc, Redwood City, CA, USA
| | - Alain Romero
- 6 Medical and Scientific Affairs, Relypsa, Inc, Redwood City, CA, USA
| | | | - Matthew R Weir
- 8 Division of Nephrology, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
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Hyun G, Li J, Bass AR, Mohapatra A, Woller SC, Lin H, Eby C, McMillin GA, Gage BF. Use of signals and systems engineering to improve the safety of warfarin initiation. J Thromb Thrombolysis 2016; 42:529-33. [PMID: 27443162 DOI: 10.1007/s11239-016-1402-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Warfarin-dosing algorithms combine clinical factors and dosing history with the current international normalized ratio (INR) to estimate the therapeutic warfarin dose. Unfortunately, these approaches can result in an overdose if the INR is spuriously low. Our goal was to develop an alert mechanism based on prior INRs in addition to the current INR. Using data from the Genetics InFormatics Trial (GIFT) of Warfarin to Prevent DVT, we analyzed warfarin dose estimates for days 3 through 11 that were ≥10 % higher than an average of the previous two dose estimates. We fit a stepwise mixed model to current and prior dose estimates, and subsequently compared the root-mean-square-error (RMSE) in predicting the final therapeutic dose using the GIFT algorithm versus the mixed model. From 861 dosing records (obtain from 556 patients), 646 dosing records (75 %) were randomly selected for the derivation cohort and 215 dosing records (25 %) for the validation cohort. Using one prior dose estimate improved the accuracy of the warfarin dose estimate. Compared to a dose estimate based on current INR (GIFT algorithm), the mixed model reduced the RMSE in the derivation cohort by 0.0015 mg/day (RMSE 0.2079 vs. 0.2094; p = 0.039). In the validation cohort, the RMSE reduction was not significant. A mixed model of dose estimates based on the current and most recent INRs shows potential to improve the safety of warfarin dosing. Clinicians should be cautious about aggressively escalating the warfarin dose after an INR that is lower than expected.
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Affiliation(s)
- G Hyun
- Washington University School of Medicine, 660 S. Euclid Ave, Campus Box 8005, St. Louis, MO, 63110, USA
| | - J Li
- Washington University School of Medicine, 660 S. Euclid Ave, Campus Box 8005, St. Louis, MO, 63110, USA
| | - A R Bass
- Hospital for Special Surgery, Weill Cornell Medical College, 535 E 70th Street, New York, NY, 10021, USA
| | - A Mohapatra
- Washington University School of Medicine, 660 S. Euclid Ave, Campus Box 8005, St. Louis, MO, 63110, USA
| | - S C Woller
- Intermountain Medical Center, 5121 Cottonwood St, Murray, UT, 84157, USA
| | - H Lin
- Washington University School of Medicine, 660 S. Euclid Ave, Campus Box 8005, St. Louis, MO, 63110, USA
| | - C Eby
- Washington University School of Medicine, 660 S. Euclid Ave, Campus Box 8005, St. Louis, MO, 63110, USA
| | - G A McMillin
- Department of Pathology and ARUP Laboratories, University of Utah, 500 Chipeta Way, Salt Lake City, UT, 84108, USA
| | - B F Gage
- Washington University School of Medicine, 660 S. Euclid Ave, Campus Box 8005, St. Louis, MO, 63110, USA.
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Baker WL, Johnson SG. Pharmacogenetics and oral antithrombotic drugs. Curr Opin Pharmacol 2016; 27:38-42. [DOI: 10.1016/j.coph.2016.01.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 01/21/2016] [Accepted: 01/29/2016] [Indexed: 01/12/2023]
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Marchant GE, Scheckel K, Campos-Outcalt D. Contrasting Medical and Legal Standards of Evidence: A Precision Medicine Case Study. THE JOURNAL OF LAW, MEDICINE & ETHICS : A JOURNAL OF THE AMERICAN SOCIETY OF LAW, MEDICINE & ETHICS 2016; 44:194-204. [PMID: 27256135 PMCID: PMC5137582 DOI: 10.1177/1073110516644210] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
As the health care system transitions to a precision medicine approach that tailors clinical care to the genetic profile of the individual patient, there is a potential tension between the clinical uptake of new technologies by providers and the legal system's expectation of the standard of care in applying such technologies. We examine this tension by comparing the type of evidence that physicians and courts are likely to rely on in determining a duty to recommend pharmacogenetic testing of patients prescribed the oral anti-coagulant drug warfarin. There is a large body of inconsistent evidence and factors for and against such testing, but physicians and courts are likely to weigh this evidence differently. The potential implications for medical malpractice risk are evaluated and discussed.
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Affiliation(s)
- Gary E. Marchant
- Corresponding author: Phone: 480-965-3246 (office); 480-388-7004 (cell); 480-727-6973 (fax);
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Shi C, Yan W, Wang G, Wang F, Li Q, Lin N. Pharmacogenetics-Based versus Conventional Dosing of Warfarin: A Meta-Analysis of Randomized Controlled Trials. PLoS One 2015; 10:e0144511. [PMID: 26672604 PMCID: PMC4682655 DOI: 10.1371/journal.pone.0144511] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 11/19/2015] [Indexed: 12/14/2022] Open
Abstract
Background Recently, using the patient’s genotype to guide warfarin dosing has gained interest; however, whether pharmacogenetics-based dosing (PD) improves clinical outcomes compared to conventional dosing (CD) remains unclear. Thus, we performed a meta-analysis to evaluate these two strategies. Methods The PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure (CNKI), Chinese VIP and Chinese Wan-fang databases were searched. The Cochrane Collaboration’s tool was used to assess the risk of bias in randomized controlled trials (RCTs). The primary outcome was time within the therapeutic range (TTR); the secondary end points were the time to maintenance dose and time to first therapeutic international normalized ratio (INR), an INR greater than 4, adverse events, major bleeding, thromboembolism and death from any cause. Results A total of 11 trials involving 2,678 patients were included in our meta-analysis. The results showed that PD did not improve the TTR compared to CD, although PD significantly shortened the time to maintenance dose (MD = -8.80; 95% CI: -11.99 to -5.60; P<0.00001) and the time to first therapeutic INR (MD = -2.80; 95% CI: -3.45 to -2.15; P<0.00001). Additionally, PD significantly reduced the risk of adverse events (RR = 0.86; 95% CI: 0.75 to 0.99; P = 0.03) and major bleeding (RR = 0.36; 95% CI: 0.15 to 0.89, P = 0.03), although it did not reduce the percentage of INR greater than 4, the risk of thromboembolic events and death from any cause. Subgroup analysis showed that PD resulted in a better improvement in the endpoints of TTR and over-anticoagulation at a fixed initial dosage rather than a non-fixed initial dosage. Conclusions The use of genotype testing in the management of warfarin anticoagulation was associated with significant improvements in INR-related and clinical outcomes. Thus, genotype-based regimens can be considered a reliable and accurate method to determine warfarin dosing and may be preferred over fixed-dose regimens. Trial Registration PROSPERO Database registration: CRD42015024127.
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Affiliation(s)
- Changcheng Shi
- Department of Clinical Pharmacy, Hangzhou First People’s Hospital, Hangzhou, Zhejiang Province, China
- Department of Clinical Pharmacology, Hangzhou Translational Medicine Research Center, Hangzhou, Zhejiang Province, China
| | - Wei Yan
- Department of Clinical Pharmacy, Hangzhou First People’s Hospital, Hangzhou, Zhejiang Province, China
| | - Gang Wang
- Department of Clinical Pharmacy, Hangzhou First People’s Hospital, Hangzhou, Zhejiang Province, China
| | - Fei Wang
- Department of Clinical Pharmacy, Hangzhou First People’s Hospital, Hangzhou, Zhejiang Province, China
- Department of Clinical Pharmacology, Hangzhou Translational Medicine Research Center, Hangzhou, Zhejiang Province, China
| | - Qingyu Li
- Department of Clinical Pharmacy, Hangzhou First People’s Hospital, Hangzhou, Zhejiang Province, China
| | - Nengming Lin
- Department of Clinical Pharmacy, Hangzhou First People’s Hospital, Hangzhou, Zhejiang Province, China
- Department of Clinical Pharmacology, Hangzhou Translational Medicine Research Center, Hangzhou, Zhejiang Province, China
- Affiliated Hangzhou Hospital, Nanjing Medical University, Hangzhou, Zhejiang Province, China
- The first Affiliated Hangzhou Hospital, Zhejiang Chinese Medical University, Hangzhou, Zhejiang Province, China
- * E-mail:
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Wise ES, Gadomski SP, McMaster WG, Wilson RJ, Nelms JK, Hocking KM, Brophy CM. The influence of VKORC1 and CYP2C9 mutations on warfarin response after total hip and knee arthroplasty. J Orthop 2015; 12:S145-51. [PMID: 27047214 DOI: 10.1016/j.jor.2015.10.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Accepted: 10/25/2015] [Indexed: 10/22/2022] Open
Abstract
AIMS This study characterizes the influence of genotype at two loci on warfarin response after arthroplasty. METHODS 121 postarthroplasty patients given warfarin thromboprophylaxis were reviewed for international normalized ratio (INR) values on the first three days postoperatively. Significant differences among genotypes in INR values on each of the first three postoperative days were assessed. RESULTS Wild-type patients at both loci (∼23% of patients) had yet to reach therapeutic INR (1.5-2.0) by postoperative day three more frequently than those with a mutation conferring hyper-responsiveness (61% vs. 30%; P ≤ .01). CONCLUSIONS Wild-type patients are not anticoagulated in a sufficiently prompt manner after arthroplasty.
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Affiliation(s)
- Eric S Wise
- Department of Surgery, Vanderbilt University Medical Center, Nashville, TN 37232-2730, USA
| | - Stephen P Gadomski
- Department of Surgery, Thomas Jefferson University Hospital, Philadelphia, PA 19107, USA
| | - William G McMaster
- Department of Surgery, Vanderbilt University Medical Center, Nashville, TN 37232-2730, USA
| | - Robert J Wilson
- Department of Surgery, Vanderbilt University Medical Center, Nashville, TN 37232-2730, USA
| | - Justin K Nelms
- Department of Surgery, University of Maryland, Baltimore Washington Medical Center, Glen Burnie, MD 21061, USA
| | - Kyle M Hocking
- Department of Surgery, Vanderbilt University Medical Center, Nashville, TN 37232-2730, USA
| | - Colleen M Brophy
- Department of Surgery, Tennessee Valley Veterans Administration, Nashville, TN 37212, USA; Department of Surgery, Vanderbilt University Medical Center, Nashville, TN 37232-2730, USA
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15
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Nam D, Nunley RM, Johnson SR, Keeney JA, Barrack RL. Mobile compression devices and aspirin for VTE prophylaxis following simultaneous bilateral total knee arthroplasty. J Arthroplasty 2015; 30:447-50. [PMID: 25453630 DOI: 10.1016/j.arth.2014.10.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 10/08/2014] [Accepted: 10/13/2014] [Indexed: 02/01/2023] Open
Abstract
Recently, Levy et al questioned the effectiveness of mobile compression devices (MCDs) as the sole method of thromboprophylaxis following simultaneous bilateral total knee arthroplasty (TKA). This study's purpose was to assess if the addition of aspirin to MCDs improves venous thromboembolism (VTE) prevention following simultaneous bilateral TKA. Ninety-six patients (192 TKAs) were retrospectively reviewed: 47 patients received MCDs for 10 days and aspirin for 6 weeks postoperatively based on a risk stratification protocol, while 49 patients received warfarin for 4 weeks postoperatively. One symptomatic VTE was noted in the warfarin cohort, while one patient in the MCD/aspirin cohort and three patients in the warfarin cohort were readmitted within 3 months of surgery. In appropriately selected patients, MCDs with aspirin shows promise in VTE prevention following simultaneous bilateral TKA.
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Affiliation(s)
- Denis Nam
- Department of Orthopedic, Surgery, Washington University School of Medicine/Barnes-Jewish Hospital, St. Louis, Missouri
| | - Ryan M Nunley
- Department of Orthopedic, Surgery, Washington University School of Medicine/Barnes-Jewish Hospital, St. Louis, Missouri
| | - Staci R Johnson
- Department of Orthopedic, Surgery, Washington University School of Medicine/Barnes-Jewish Hospital, St. Louis, Missouri
| | - James A Keeney
- Department of Orthopedic, Surgery, Washington University School of Medicine/Barnes-Jewish Hospital, St. Louis, Missouri
| | - Robert L Barrack
- Department of Orthopedic, Surgery, Washington University School of Medicine/Barnes-Jewish Hospital, St. Louis, Missouri
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16
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Nam D, Sadhu A, Hirsh J, Keeney JA, Nunley RM, Barrack RL. The use of warfarin for DVT prophylaxis following hip and knee arthroplasty: how often are patients within their target INR range? J Arthroplasty 2015; 30:315-9. [PMID: 25261182 PMCID: PMC4324127 DOI: 10.1016/j.arth.2014.08.032] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 08/25/2014] [Accepted: 08/27/2014] [Indexed: 02/01/2023] Open
Abstract
The purpose of this study was to determine the percentage of time that patients are therapeutic when prescribed warfarin for chemical thromboprophylaxis following a hip or knee arthroplasty procedure. One hundred eighty-four patients receiving warfarin for 4weeks postoperatively, dosed using a Web-application accounting for patient demographics, INR levels, and concomitant medication use, were included. Patients with a target INR range between 1.7 and 2.7 were therapeutic for only 54.4% of the time (32.5% subtherapeutic, 13.0% supratherapeutic) while patients with a target INR range between 2.0 and 3.0 were therapeutic for only 45.9% of the time (39.2% subtherapeutic, 14.8% supratherapeutic). Patients receiving warfarin for chemical thromboprophylaxis are within their targeted INR range for only a limited period of time during their postoperative course.
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Affiliation(s)
- Denis Nam
- Washington University School of Medicine/Barnes-Jewish Hospital, Department of Orthopedic Surgery, St. Louis, Missouri
| | - Anita Sadhu
- Washington University School of Medicine/Barnes-Jewish Hospital, Department of Orthopedic Surgery, St. Louis, Missouri
| | - Jeffrey Hirsh
- Washington University School of Medicine/Barnes-Jewish Hospital, Department of Orthopedic Surgery, St. Louis, Missouri
| | - James A Keeney
- Washington University School of Medicine/Barnes-Jewish Hospital, Department of Orthopedic Surgery, St. Louis, Missouri
| | - Ryan M Nunley
- Washington University School of Medicine/Barnes-Jewish Hospital, Department of Orthopedic Surgery, St. Louis, Missouri
| | - Robert L Barrack
- Washington University School of Medicine/Barnes-Jewish Hospital, Department of Orthopedic Surgery, St. Louis, Missouri
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Verhoef TI, Redekop WK, Daly AK, van Schie RMF, de Boer A, Maitland-van der Zee AH. Pharmacogenetic-guided dosing of coumarin anticoagulants: algorithms for warfarin, acenocoumarol and phenprocoumon. Br J Clin Pharmacol 2014; 77:626-41. [PMID: 23919835 DOI: 10.1111/bcp.12220] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 07/17/2013] [Indexed: 12/13/2022] Open
Abstract
Coumarin derivatives, such as warfarin, acenocoumarol and phenprocoumon are frequently prescribed oral anticoagulants to treat and prevent thromboembolism. Because there is a large inter-individual and intra-individual variability in dose-response and a small therapeutic window, treatment with coumarin derivatives is challenging. Certain polymorphisms in CYP2C9 and VKORC1 are associated with lower dose requirements and a higher risk of bleeding. In this review we describe the use of different coumarin derivatives, pharmacokinetic characteristics of these drugs and differences amongst the coumarins. We also describe the current clinical challenges and the role of pharmacogenetic factors. These genetic factors are used to develop dosing algorithms and can be used to predict the right coumarin dose. The effectiveness of this new dosing strategy is currently being investigated in clinical trials.
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Affiliation(s)
- Talitha I Verhoef
- Department of Pharmaceutical Sciences, Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht University, Utrecht
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Tang Q, Zou H, Guo C, Liu Z. Outcomes of pharmacogenetics-guided dosing of warfarin: a systematic review and meta-analysis. Int J Cardiol 2014; 175:587-91. [PMID: 25005340 DOI: 10.1016/j.ijcard.2014.06.031] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 06/19/2014] [Accepted: 06/24/2014] [Indexed: 11/25/2022]
Affiliation(s)
- Qinghui Tang
- Department of Cardiology of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, China
| | - Houjuan Zou
- Department of Cardiology of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, China
| | - Caihong Guo
- Department of Cardiology of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, China
| | - Zhengxiang Liu
- Department of Cardiology of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, China.
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Levran O, Peles E, Randesi M, Shu X, Ott J, Shen PH, Adelson M, Kreek MJ. Association of genetic variation in pharmacodynamic factors with methadone dose required for effective treatment of opioid addiction. Pharmacogenomics 2014; 14:755-68. [PMID: 23651024 DOI: 10.2217/pgs.13.58] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
AIM The interindividual variability in the dose required for effective methadone maintenance treatment (MMT) for opioid addiction may be influenced in part by genetic variations in genes encoding pharmacodynamic factors of methadone. This study was conducted to identify some of these variants. MATERIALS & METHODS This study focused on 11 genes encoding components of the opioidergic (OPRM1, POMC and ARRB2), the dopaminergic (ANKK1 and DRD2) and the glutamatergic pathways (GRIN1 and GRIN2A), as well as the neurotrophin system (NGFB, BDNF, NTRK1 and NTRK2). The study includes 227 Israeli patients undergoing stable MMT. RESULTS Out of the 110 variants analyzed, 12 SNPs (in BDNF, NTRK2, OPRM1, DRD2 and ANKK1) were associated with methadone dose (nominal p < 0.05). Of these SNPs, ANKK1 rs7118900 and DRD2 rs2283265 are known to affect gene expression. Logistic regression of five representative SNPs discriminated between individuals requiring a methadone dose of >120 mg/day and <120 mg/day (p = 0.019), and showed moderate sensitivity and specificity (AUC of 0.63 in receiver operating characteristic analysis). CONCLUSION This data should stimulate further research on the potential influence and clinical significance of these variants on MMT.
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Affiliation(s)
- Orna Levran
- Laboratory of the Biology of Addictive Diseases, The Rockefeller University, New York, NY, USA.
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CYP2C9, VKORC1, CYP4F2, ABCB1 and F5 variants: influence on quality of long-term anticoagulation. Pharmacol Rep 2014; 66:243-9. [PMID: 24911077 DOI: 10.1016/j.pharep.2013.09.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 08/19/2013] [Accepted: 09/06/2013] [Indexed: 11/22/2022]
Abstract
AIMS The study aims to evaluate the impact of genetic, demographic and clinical data on various measures of outcome of anticoagulation quality in patients. PATIENTS AND METHODS The study consisted of 310 patients receiving long-term oral anticoagulation therapy in our hospital. Apart from demographic and clinical variables, 21 SNPs (in 7 genes) were analyzed and compared with the outcomes of anticoagulation therapy. Various outcomes that were measured are; supra therapeutic INRs (INR >3, >6), anticoagulation stabilization, time taken to stabilize and proportion of INRs within (2-3), above (>3) and below (<2) therapeutic range. RESULTS Supra therapeutic INRs were influenced by CYP2C9*2, *3, CYP4F2 rs2108622, VKORC1-1639G>A, 1173C>T, rs55894764 along with concomitant drugs, smoking, body weight and height. Persistently fluctuating INRs/absolute instability correlated with VKORC1-1639G>A, gender, height and body mass index. The time taken to stabilize was associated with CYP4F2 rs2108622, CYP2C9*14, smoking, clinical indication and concomitant drugs. The overall distribution of INR was influenced by variants in CYP4F2 rs2108622, CYP2C9*3, rs9332230, VKORC1 1173C>T, -1639G>A, rs55894764, ABCB1 rs2032582, rs1128503, rs1045642 and F5 rs6025, age, smoking and concomitant drugs. CONCLUSIONS Knowledge of factors influencing the quality of long term anticoagulation can help clinicians to customize therapy either by dose variation, therapy with alternate choice of drug, concurrent heparin therapy and/or frequent INR monitoring.
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Dorfman R, Khayat Z, Sieminowski T, Golden B, Lyons R. Application of personalized medicine to chronic disease: a feasibility assessment. Clin Transl Med 2013; 2:16. [PMID: 24351097 PMCID: PMC3878365 DOI: 10.1186/2001-1326-2-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 09/25/2013] [Indexed: 02/04/2023] Open
Abstract
Personalized Medicine has the potential to improve health outcomes and reduce the cost of care; however its adoption has been slow in Canada. Bridgepoint Health is a complex continuous care provider striving to reduce the burden of polypharmacy in chronic patients. The main goal of the study was to explore the feasibility of utilizing personalized medicine in the treatment of chronic complex patients as a preliminary institutional health technology assessment. We analyzed stroke treatment optimization as a clinical indication that could serve as a "proof of concept" for the widespread implementation of pharmacogenetics. The objectives of the study were three-fold:1. Review current practice in medication administration for stroke treatment at Bridgepoint Health2. Critically analyze evidence that pharmacogenetic testing could (or could not) enhance drug selection and treatment efficacy for stroke patients;3. Assess the cost-benefit potential of a pharmacogenetic intervention for stroke.Review current practice in medication administration for stroke treatment at Bridgepoint HealthCritically analyze evidence that pharmacogenetic testing could (or could not) enhance drug selection and treatment efficacy for stroke patients;Assess the cost-benefit potential of a pharmacogenetic intervention for stroke.We conducted a review of stroke treatment practices at Bridgepoint Health, scanned the literature for drug-gene and drug-outcome interactions, and evaluated the potential consequences of pharmacogenetic testing using the ACCE model.There is a substantial body of evidence suggesting that pharmacogenetic stratification of stroke treatment can improve patient outcomes in the long-term, and provide substantial efficiencies for the healthcare system in the short-term. Specifically, pharmacogenetic stratification of antiplatelet and anticoagulant therapies for stroke patients may have a major impact on the risk of disease recurrence, and thus should be explored further for clinical application. Bridgepoint Health, and other healthcare institutions taking this path, should consider launching pilot projects to assess the practical impact of pharmacogenetics to optimize treatment for chronic continuous care.
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Affiliation(s)
- Ruslan Dorfman
- Present Address: Geneyouin Inc, Maple, ON, Canada
- The Rotman School of Management, The University of Toronto, Toronto, ON, Canada
| | - Zayna Khayat
- The Rotman School of Management, The University of Toronto, Toronto, ON, Canada
- International Centre for Health Innovation, Richard Ivey School of Business, University of Western Ontario, London, ON, Canada
| | | | - Brian Golden
- International Centre for Health Innovation, Richard Ivey School of Business, University of Western Ontario, London, ON, Canada
| | - Renee Lyons
- Bridgepoint Chair in Complex Chronic Disease Research, TD Scientific Director, Bridgepoint Collaboratory for Research and Innovation, Toronto, Ontario, Canada
- Dalla Lana School of Public Health, The University of Toronto, Toronto, ON, Canada
- Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada
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Verhoef TI, Ragia G, de Boer A, Barallon R, Kolovou G, Kolovou V, Konstantinides S, Le Cessie S, Maltezos E, van der Meer FJM, Redekop WK, Remkes M, Rosendaal FR, van Schie RMF, Tavridou A, Tziakas D, Wadelius M, Manolopoulos VG, Maitland-van der Zee AH. A randomized trial of genotype-guided dosing of acenocoumarol and phenprocoumon. N Engl J Med 2013; 369:2304-12. [PMID: 24251360 DOI: 10.1056/nejmoa1311388] [Citation(s) in RCA: 186] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Observational evidence suggests that the use of a genotype-guided dosing algorithm may increase the effectiveness and safety of acenocoumarol and phenprocoumon therapy. METHODS We conducted two single-blind, randomized trials comparing a genotype-guided dosing algorithm that included clinical variables and genotyping for CYP2C9 and VKORC1 with a dosing algorithm that included only clinical variables, for the initiation of acenocoumarol or phenprocoumon treatment in patients with atrial fibrillation or venous thromboembolism. The primary outcome was the percentage of time in the target range for the international normalized ratio (INR; target range, 2.0 to 3.0) in the 12-week period after the initiation of therapy. Owing to low enrollment, the two trials were combined for analysis. The primary outcome was assessed in patients who remained in the trial for at least 10 weeks. RESULTS A total of 548 patients were enrolled (273 patients in the genotype-guided group and 275 in the control group). The follow-up was at least 10 weeks for 239 patients in the genotype-guided group and 245 in the control group. The percentage of time in the therapeutic INR range was 61.6% for patients receiving genotype-guided dosing and 60.2% for those receiving clinically guided dosing (P=0.52). There were no significant differences between the two groups for several secondary outcomes. The percentage of time in the therapeutic range during the first 4 weeks after the initiation of treatment in the two groups was 52.8% and 47.5% (P=0.02), respectively. There were no significant differences with respect to the incidence of bleeding or thromboembolic events. CONCLUSIONS Genotype-guided dosing of acenocoumarol or phenprocoumon did not improve the percentage of time in the therapeutic INR range during the 12 weeks after the initiation of therapy. (Funded by the European Commission Seventh Framework Programme and others; EU-PACT ClinicalTrials.gov numbers, NCT01119261 and NCT01119274.).
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Apostolakis S, Sullivan RM, Olshansky B, Lip GYH. Factors Affecting Quality of Anticoagulation Control Among Patients With Atrial Fibrillation on Warfarin. Chest 2013; 144:1555-1563. [PMID: 23669885 DOI: 10.1378/chest.13-0054] [Citation(s) in RCA: 366] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Affiliation(s)
- Stavros Apostolakis
- University of Birmingham Centre for Cardiovascular Sciences, City Hospital, Birmingham, England
| | - Renee M Sullivan
- Division of Cardiovascular Medicine University of Iowa Hospitals and Clinics, Iowa City, IA
| | - Brian Olshansky
- Division of Cardiovascular Medicine University of Iowa Hospitals and Clinics, Iowa City, IA
| | - Gregory Y H Lip
- University of Birmingham Centre for Cardiovascular Sciences, City Hospital, Birmingham, England.
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Abstract
PURPOSE OF REVIEW To review the most promising genetic markers associated with the variability in the safety or efficacy of warfarin and clopidogrel and highlight the verification and validation initiatives for translating clopidogrel and warfarin pharmacogenetic tests to clinical practice. RECENT FINDINGS Rapid advances in pharmacogenetics, continuous decrease in genotyping cost, development of point-of-care devices and the newly established clinical genotyping programs at several institutions hold the promise of individualizing clopidogrel and warfarin based on genotype. Guidelines have been established to assist clinicians in prescribing clopidogrel or warfarin dose based on genotype. However, the clinical utility of clopidogrel and warfarin is still limited. Accordingly, large randomized clinical trials are underway to define the role of clopidogrel and warfarin pharmacogenetics in clinical practice. SUMMARY Pharmacogenetics has offered compelling evidence toward the individualization of clopidogrel and warfarin therapies. The rapid advances in technology make the clinical implementation of clopidogrel and warfarin pharmacogenetics possible. The clinical genotyping programs and the ongoing clinical trials will help in overcoming some of the barriers facing the clinical implementation of clopidogrel and warfarin pharmacogenetics.
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Cardelli M, Marchegiani F, Corsonello A, Lattanzio F, Provinciali M. A review of pharmacogenetics of adverse drug reactions in elderly people. Drug Saf 2013; 35 Suppl 1:3-20. [PMID: 23446782 DOI: 10.1007/bf03319099] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Older adults are more susceptible to the prevalence of therapeutic failure and adverse drug reactions (ADRs). Recent advances in genomic research have shed light on the crucial role of genetic variants, mainly involving genes encoding drug-metabolizing enzymes, drug transporters and genes responsible for a compound's mechanism of action, in driving different treatment responses among individuals, in terms of therapeutic efficacy and safety. The interindividual variations of these genes may account for the differences observed in drug efficacy and the appearance of ADRs in elderly people. The advent of whole genome mapping techniques has allowed researchers to begin to characterize the genetic components underlying serious ADRs. The identification and validation of these genetic markers will enable the screening of patients at risk of serious ADRs and to establish personalized treatment regimens.The aim of this review was to provide an update on the recent developments in geriatric pharmacogenetics in clinical practice by reviewing the available evidence in the PubMed database to September 2012. A Pubmed search was performed (years 1999-2012) using the following two search strategies: ('pharmacogenomic' OR 'pharmacogenetic ') AND ('geriatric' or 'elderly ') AND 'adverse drug reactions'; [gene name] AND ('geriatric' or 'elderly ') AND 'adverse drug reactions', in which the gene names were those contained in the Table of Pharmacogenomic Biomarkers in Drug Labels published online by the US Food and Drug Administration ( http://www.fda.gov/drugs/scienceresearch/researchareas/pharmacogenetics/ucm083378.htm ). Reference lists of included original articles and relevant review articles were also screened. The search was limited to studies published in the English language.
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Affiliation(s)
- Maurizio Cardelli
- Advanced Technology Center for Aging Research, Scientific Technological Area, IRCCS-INRCA, Via Birarelli 8, 60121, Ancona, Italy
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Abstract
Since the introduction in the 1950s, warfarin has become the commonly used oral anticoagulant for the prevention of thromboembolism in patients with deep vein thrombosis, atrial fibrillation or prosthetic heart valve replacement. Warfarin is highly efficacious; however, achieving the desired anticoagulation is difficult because of its narrow therapeutic window and highly variable dose response among individuals. Bleeding is often associated with overdose of warfarin. There is overwhelming evidence that an individual's warfarin maintenance is associated with clinical factors and genetic variations, most notably polymorphisms in cytochrome P450 2C9 and vitamin K epoxide reductase subunit 1. Numerous dose-prediction algorithms incorporating both genetic and clinical factors have been developed and tested clinically. However, results from major clinical trials are not available yet. This review aims to provide an overview of the field of warfarin which includes information about the drug, genetics of warfarin dose requirements, dosing algorithms developed and the challenges for the clinical implementation of warfarin pharmacogenetics.
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Wen MS, Lee MTM. Warfarin Pharmacogenetics: New Life for an Old Drug. ACTA CARDIOLOGICA SINICA 2013; 29:235-242. [PMID: 27122712 PMCID: PMC4804835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 04/26/2013] [Indexed: 06/05/2023]
Abstract
UNLABELLED Warfarin was first introduced in the 1950s and quickly became the most commonly used oral anticoagulant for the prevention of thromboembolism in patients with deep vein thrombosis, atrial fibrillation, or prosthetic heart valve replacement. Warfarin is highly effective in treating these diseases; however, several factors prevent it from even wider use, especially in Asian populations. It is difficult for patients on warfarin to reach desired anticoagulation due to its narrow therapeutic index and highly variable dose response. The major adverse event is bleeding which is associated with overdose of warfarin. Clinical and genetic factors such as polymorphisms in CYP2C9 and VKORC1 associated with an individual's warfarin maintenance have been identified. More than 20 dose prediction algorithms incorporating both genetic and clinical factors have been developed, and some of them have been tested clinically. However, most of the algorithms were tested in small populations. Several major clinical trials are now underway. This review aims to provide an overview of the field of warfarin which includes information about the drug, genetics of warfarin dose requirements, dosing algorithms developed and the challenges of clinical implementation of warfarin pharmacogenetics. KEY WORDS CYP2C9; Pharmacogenetics; VKORC1; Warfarin.
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Affiliation(s)
- Ming-Shien Wen
- Second Section of Cardiology, Department of Medicine, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - Ming Ta Michael Lee
- Laboratory for International Alliance, RIKEN Center for Genomic Medicine, Yokohama, Japan
- 3Institute of Biomedical Sciences, Academia Sinica, Taipei
- Graduate Institute of Chinese Medical Science, China Medical University, Taichung, Taiwan
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Abstract
After a decade of clinical investigation, pharmacogenetic-guided initial dosing of warfarin is at a crossroads. Genotypes for two single nucleotide polymorphisms (SNPs) in the cytochrome P 450 2C9 gene, affecting warfarin metabolism, and one SNP in vitamin K reductase complex 1 gene, affecting warfarin sensitivity, account for approximately 30% of therapeutic warfarin dosing variability in whites and Asians. Incorporating this genetic information, along with patient's age, body size, and other clinical information improves the accuracy of initial warfarin dosing. Currently, there is insufficient evidence to support the clinical benefits and cost effectiveness of routine warfarin pharmacogenetics. Results from ongoing international randomized clinical trials should provide clarity about the place of warfarin pharmacogenetics in personalized medicine.
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Affiliation(s)
- Charles Eby
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, Missouri, USA.
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31
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Fung E, Patsopoulos NA, Belknap SM, O'Rourke DJ, Robb JF, Anderson JL, Shworak NW, Moore JH. Effect of genetic variants, especially CYP2C9 and VKORC1, on the pharmacology of warfarin. Semin Thromb Hemost 2012; 38:893-904. [PMID: 23041981 DOI: 10.1055/s-0032-1328891] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The genes encoding the cytochrome P450 2C9 enzyme (CYP2C9) and vitamin K-epoxide reductase complex unit 1 (VKORC1) are major determinants of anticoagulant response to warfarin. Together with patient demographics and clinical information, they account for approximately one-half of the warfarin dose variance in individuals of European descent. Recent prospective and randomized controlled trial data support pharmacogenetic guidance with their use in warfarin dose initiation and titration. Benefits from pharmacogenetics-guided warfarin dosing have been reported to extend beyond the period of initial dosing, with supportive data indicating benefits to at least 3 months. The genetic effects of VKORC1 and CYP2C9 in African and Asian populations are concordant with those in individuals of European ancestry; however, frequency distribution of allelic variants can vary considerably between major populations. Future randomized controlled trials in multiethnic settings using population-specific dosing algorithms will allow us to further ascertain the generalizability and cost-effectiveness of pharmacogenetics-guided warfarin therapy. Additional genome-wide association studies may help us to improve and refine dosing algorithms and potentially identify novel biological pathways.
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Affiliation(s)
- Erik Fung
- Section of Cardiology, Heart & Vascular Center, Lebanon, New Hampshire 03756, USA.
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Do EJ, Lenzini P, Eby CS, Bass AR, McMillin GA, Stevens SM, Woller SC, Pendleton RC, Anderson JL, Proctor P, Nunley RM, Davila-Roman V, Gage BF. Genetics informatics trial (GIFT) of warfarin to prevent deep vein thrombosis (DVT): rationale and study design. THE PHARMACOGENOMICS JOURNAL 2012; 12:417-24. [PMID: 21606949 PMCID: PMC3175019 DOI: 10.1038/tpj.2011.18] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2010] [Revised: 04/12/2011] [Accepted: 04/18/2011] [Indexed: 11/09/2022]
Abstract
The risk of venous thromboembolism (VTE) is higher after the total hip or knee replacement surgery than after almost any other surgical procedure; warfarin sodium is commonly prescribed to reduce this peri-operative risk. Warfarin has a narrow therapeutic window with high inter-individual dose variability and can cause hemorrhage. The genetics-informatics trial (GIFT) of warfarin to prevent deep vein thrombosis (DVT) is a 2 × 2 factorial-design, randomized controlled trial designed to compare the safety and effectiveness of warfarin-dosing strategies. GIFT will answer two questions: (1) does pharmacogenetic (PGx) dosing reduce the rate of adverse events in orthopedic patients; and (2) is a lower target international normalized ratio (INR) non-inferior to a higher target INR in orthopedic participants? The composite primary endpoint of the trial is symptomatic and asymptomatic VTE (identified on screening ultrasonography), major hemorrhage, INR ≥ 4, and death.
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Affiliation(s)
- Elizabeth J. Do
- Dept of Internal Medicine, Washington University, St. Louis, MO, USA
| | - Petra Lenzini
- Dept of Internal Medicine, Washington University, St. Louis, MO, USA
| | - Charles S. Eby
- Dept of Internal Medicine, Washington University, St. Louis, MO, USA
- Dept of Pathology, Washington University, St Louis, MO, USA
| | | | | | | | | | | | | | - Pam Proctor
- Dept of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Ryan M. Nunley
- Dept of Orthopedic Surgery, Washington University, St. Louis, MO, USA
| | | | - Brian F. Gage
- Dept of Internal Medicine, Washington University, St. Louis, MO, USA
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Ichimura Y, Takahashi H, Lee MTM, Shiomi M, Mihara K, Morita T, Chen YT, Echizen H. Inter-Individual Differences in Baseline Coagulation Activities and Their Implications for International Normalized Ratio Control During Warfarin Initiation Therapy. Clin Pharmacokinet 2012; 51:799-808. [DOI: 10.1007/s40262-012-0009-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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34
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Jorgensen AL, FitzGerald RJ, Oyee J, Pirmohamed M, Williamson PR. Influence of CYP2C9 and VKORC1 on patient response to warfarin: a systematic review and meta-analysis. PLoS One 2012; 7:e44064. [PMID: 22952875 PMCID: PMC3430615 DOI: 10.1371/journal.pone.0044064] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 07/30/2012] [Indexed: 01/13/2023] Open
Abstract
Background Warfarin is a highly effective anticoagulant however its effectiveness relies on maintaining INR in therapeutic range. Finding the correct dose is difficult due to large inter-individual variability. Two genes, CYP2C9 and VKORC1, have been associated with this variability, leading to genotype-guided dosing tables in warfarin labeling. Nonetheless, it remains unclear how genotypic information should be used in practice. Navigating the literature to determine how genotype will influence warfarin response in a particular patient is difficult, due to significant variation in patient ethnicity, outcomes investigated, study design, and methodological rigor. Our systematic review was conducted to enable fair and accurate interpretation of which variants affect which outcomes, in which patients, and to what extent. Methodology/Principal Findings A comprehensive search strategy was applied and 117 studies included. Primary outcomes were stable dose, time to stable dose and bleeding events. Methodological quality was assessed using criteria of Jorgensen and Williamson and data synthesized in meta-analyses using advanced methods. Pooled effect estimates were significant in most ethnic groups for CYP2C9*3 and stable dose (mutant types requiring between 1.1(0.7–1.5) and 2.3 (1.6–3.0)mg/day). Effect estimates were also significant for VKORC1 and stable dose for most ethnicities, although direction differed between asians and non-asians (mutant types requiring between 0.8(0.4–1.3) and 1.5(1.1–1.8)mg/day more in asians and between 1.5(0.7–2.2) and 3.1(2.7–3.6)mg/day less in non-asians). Several studies were excluded due to inadequate data reporting. Assessing study quality highlighted significant variability in methodological rigor. Notably, there was significant evidence of selective reporting, of outcomes and analysis approaches. Conclusions/Significance Genetic associations with warfarin response vary between ethnicities. In order to achieve unbiased estimates in different populations, a high level of methodological rigor must be maintained and studies should report sufficient data to enable inclusion in meta-analyses. We propose minimum reporting requirements, suggest methodological guidelines and provide recommendations for reducing the risk of selective reporting.
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Affiliation(s)
- Andrea L Jorgensen
- Department of Biostatistics, Shelley's Cottage, University of Liverpool, Liverpool, United Kingdom.
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36
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Abstract
Pharmacogenetic/pharmacogenomic (PGx) approaches to psychopharmacology aim to identify clinically meaningful predictors of drug efficacy and/or side-effect burden. To date, however, PGx studies in psychiatry have not yielded compelling results, and clinical utilization of PGx testing in psychiatry is extremely limited. In this review, the authors provide a brief overview on the status of PGx studies in psychiatry, review the commercialization process for PGx tests and then discuss methodological considerations that may enhance the potential for clinically applicable PGx tests in psychiatry. The authors focus on design considerations that include increased ascertainment of subjects in the earliest phases of illness, discuss the advantages of drug-induced adverse events as phenotypes for examination and emphasize the importance of maximizing adherence to treatment in pharmacogenetic studies. Finally, the authors discuss unique aspects of pharmacogenetic studies that may distinguish them from studies of other complex traits. Taken together, these data provide insights into the design and methodological considerations that may enhance the potential for clinical utility of PGx studies.
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Motsinger-Reif AA, Wagner MJ. Research Highlights: Highlights from the latest articles in pharmacogenomics of warfarin dosing. Pharmacogenomics 2012; 13:861-3. [DOI: 10.2217/pgs.12.65] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Affiliation(s)
- Alison A Motsinger-Reif
- Bioinformatics Research Center, Department of Statistics, North Carolina State University, NC, USA
| | - Michael J Wagner
- Institute for Pharmacogenomics & Individualized Therapy, University of North Carolina at Chapel Hill, NC, USA
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38
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Lund K, Gaffney D, Spooner R, Etherington AM, Tansey P, Tait RC. Polymorphisms inVKORC1have more impact thanCYP2C9polymorphisms on early warfarin International Normalized Ratio control and bleeding rates. Br J Haematol 2012; 158:256-261. [DOI: 10.1111/j.1365-2141.2012.09150.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2012] [Accepted: 03/27/2012] [Indexed: 12/18/2022]
Affiliation(s)
- Kirstin Lund
- Department of Haematology; Royal Infirmary; Glasgow UK
| | - Dairena Gaffney
- Department of Clinical Biochemistry; Royal Infirmary; Glasgow UK
| | - Richard Spooner
- Department of Clinical Biochemistry; Royal Infirmary; Glasgow UK
| | | | - Patrick Tansey
- Department of Haematology; Victoria Infirmary; Glasgow UK
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Anderson JL, Horne BD, Stevens SM, Woller SC, Samuelson KM, Mansfield JW, Robinson M, Barton S, Brunisholz K, Mower CP, Huntinghouse JA, Rollo JS, Siler D, Bair TL, Knight S, Muhlestein JB, Carlquist JF. A Randomized and Clinical Effectiveness Trial Comparing Two Pharmacogenetic Algorithms and Standard Care for Individualizing Warfarin Dosing (CoumaGen-II). Circulation 2012; 125:1997-2005. [DOI: 10.1161/circulationaha.111.070920] [Citation(s) in RCA: 188] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background—
Warfarin is characterized by marked variations in individual dose requirements and a narrow therapeutic window. Pharmacogenetics (PG) could improve dosing efficiency and safety, but clinical trials evidence is meager.
Methods and Results—
A Randomized and Clinical Effectiveness Trial Comparing Two Pharmacogenetic Algorithms and Standard Care for Individualizing Warfarin Dosing (CoumaGen-II) comprised 2 comparisons: (1) a blinded, randomized comparison of a modified 1-step (PG-1) with a 3-step algorithm (PG-2) (N=504), and (2) a clinical effectiveness comparison of PG guidance with use of either algorithm with standard dosing in a parallel control group (N=1866). A rapid method provided same-day
CYP2C9
and
VKORC1
genotyping. Primary outcomes were percentage of out-of-range international normalized ratios at 1 and 3 months and percentage of time in therapeutic range. Primary analysis was modified intention to treat. In the randomized comparison, PG-2 was noninferior but not superior to PG-1 for percentage of out-of-range international normalized ratios at 1 month and 3 months and for percentage of time in therapeutic range at 3 months. However, the combined PG cohort was superior to the parallel controls (percentage of out-of-range international normalized ratios 31% versus 42% at 1 month; 30% versus 42% at 3 months; percentage of time in therapeutic range 69% versus 58%, 71% versus 59%, respectively, all
P
<0.001). Differences persisted after adjustment for age, sex, and clinical indication. There were fewer percentage international normalized ratios ≥4 and ≤1.5 and serious adverse events at 3 months (4.5% versus 9.4% of patients,
P
<0.001) with PG guidance.
Conclusions—
These findings suggest that PG dosing should be considered for broader clinical application, a proposal that is being tested further in 3 major randomized trials. The simpler 1-step PG algorithm provided equivalent results and may be preferable for clinical application.
Clinical Trial Registration—
URL:
http://www.clinicaltrials.gov
. Unique identifier: NCT00927862.
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Affiliation(s)
- Jeffrey L. Anderson
- From the Intermountain Healthcare (Intermountain Medical Center and LDS and McKay-Dee Hospitals), Murray, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., J.W.M., M.R., S.B., K.B., C.P.M., J.A.H., J.S.R., D.S., T.L.B., S.K., J.B.M., J.F.C.); and University of Utah School of Medicine, Salt Lake City, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., S.B., K.B., S.K., J.B.M., J.F.C.)
| | - Benjamin D. Horne
- From the Intermountain Healthcare (Intermountain Medical Center and LDS and McKay-Dee Hospitals), Murray, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., J.W.M., M.R., S.B., K.B., C.P.M., J.A.H., J.S.R., D.S., T.L.B., S.K., J.B.M., J.F.C.); and University of Utah School of Medicine, Salt Lake City, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., S.B., K.B., S.K., J.B.M., J.F.C.)
| | - Scott M. Stevens
- From the Intermountain Healthcare (Intermountain Medical Center and LDS and McKay-Dee Hospitals), Murray, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., J.W.M., M.R., S.B., K.B., C.P.M., J.A.H., J.S.R., D.S., T.L.B., S.K., J.B.M., J.F.C.); and University of Utah School of Medicine, Salt Lake City, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., S.B., K.B., S.K., J.B.M., J.F.C.)
| | - Scott C. Woller
- From the Intermountain Healthcare (Intermountain Medical Center and LDS and McKay-Dee Hospitals), Murray, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., J.W.M., M.R., S.B., K.B., C.P.M., J.A.H., J.S.R., D.S., T.L.B., S.K., J.B.M., J.F.C.); and University of Utah School of Medicine, Salt Lake City, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., S.B., K.B., S.K., J.B.M., J.F.C.)
| | - Kent M. Samuelson
- From the Intermountain Healthcare (Intermountain Medical Center and LDS and McKay-Dee Hospitals), Murray, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., J.W.M., M.R., S.B., K.B., C.P.M., J.A.H., J.S.R., D.S., T.L.B., S.K., J.B.M., J.F.C.); and University of Utah School of Medicine, Salt Lake City, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., S.B., K.B., S.K., J.B.M., J.F.C.)
| | - Justin W. Mansfield
- From the Intermountain Healthcare (Intermountain Medical Center and LDS and McKay-Dee Hospitals), Murray, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., J.W.M., M.R., S.B., K.B., C.P.M., J.A.H., J.S.R., D.S., T.L.B., S.K., J.B.M., J.F.C.); and University of Utah School of Medicine, Salt Lake City, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., S.B., K.B., S.K., J.B.M., J.F.C.)
| | - Michelle Robinson
- From the Intermountain Healthcare (Intermountain Medical Center and LDS and McKay-Dee Hospitals), Murray, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., J.W.M., M.R., S.B., K.B., C.P.M., J.A.H., J.S.R., D.S., T.L.B., S.K., J.B.M., J.F.C.); and University of Utah School of Medicine, Salt Lake City, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., S.B., K.B., S.K., J.B.M., J.F.C.)
| | - Stephanie Barton
- From the Intermountain Healthcare (Intermountain Medical Center and LDS and McKay-Dee Hospitals), Murray, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., J.W.M., M.R., S.B., K.B., C.P.M., J.A.H., J.S.R., D.S., T.L.B., S.K., J.B.M., J.F.C.); and University of Utah School of Medicine, Salt Lake City, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., S.B., K.B., S.K., J.B.M., J.F.C.)
| | - Kim Brunisholz
- From the Intermountain Healthcare (Intermountain Medical Center and LDS and McKay-Dee Hospitals), Murray, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., J.W.M., M.R., S.B., K.B., C.P.M., J.A.H., J.S.R., D.S., T.L.B., S.K., J.B.M., J.F.C.); and University of Utah School of Medicine, Salt Lake City, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., S.B., K.B., S.K., J.B.M., J.F.C.)
| | - Chrissa P. Mower
- From the Intermountain Healthcare (Intermountain Medical Center and LDS and McKay-Dee Hospitals), Murray, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., J.W.M., M.R., S.B., K.B., C.P.M., J.A.H., J.S.R., D.S., T.L.B., S.K., J.B.M., J.F.C.); and University of Utah School of Medicine, Salt Lake City, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., S.B., K.B., S.K., J.B.M., J.F.C.)
| | - John A. Huntinghouse
- From the Intermountain Healthcare (Intermountain Medical Center and LDS and McKay-Dee Hospitals), Murray, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., J.W.M., M.R., S.B., K.B., C.P.M., J.A.H., J.S.R., D.S., T.L.B., S.K., J.B.M., J.F.C.); and University of Utah School of Medicine, Salt Lake City, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., S.B., K.B., S.K., J.B.M., J.F.C.)
| | - Jeffrey S. Rollo
- From the Intermountain Healthcare (Intermountain Medical Center and LDS and McKay-Dee Hospitals), Murray, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., J.W.M., M.R., S.B., K.B., C.P.M., J.A.H., J.S.R., D.S., T.L.B., S.K., J.B.M., J.F.C.); and University of Utah School of Medicine, Salt Lake City, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., S.B., K.B., S.K., J.B.M., J.F.C.)
| | - Dustin Siler
- From the Intermountain Healthcare (Intermountain Medical Center and LDS and McKay-Dee Hospitals), Murray, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., J.W.M., M.R., S.B., K.B., C.P.M., J.A.H., J.S.R., D.S., T.L.B., S.K., J.B.M., J.F.C.); and University of Utah School of Medicine, Salt Lake City, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., S.B., K.B., S.K., J.B.M., J.F.C.)
| | - Tami L. Bair
- From the Intermountain Healthcare (Intermountain Medical Center and LDS and McKay-Dee Hospitals), Murray, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., J.W.M., M.R., S.B., K.B., C.P.M., J.A.H., J.S.R., D.S., T.L.B., S.K., J.B.M., J.F.C.); and University of Utah School of Medicine, Salt Lake City, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., S.B., K.B., S.K., J.B.M., J.F.C.)
| | - Stacey Knight
- From the Intermountain Healthcare (Intermountain Medical Center and LDS and McKay-Dee Hospitals), Murray, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., J.W.M., M.R., S.B., K.B., C.P.M., J.A.H., J.S.R., D.S., T.L.B., S.K., J.B.M., J.F.C.); and University of Utah School of Medicine, Salt Lake City, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., S.B., K.B., S.K., J.B.M., J.F.C.)
| | - Joseph B. Muhlestein
- From the Intermountain Healthcare (Intermountain Medical Center and LDS and McKay-Dee Hospitals), Murray, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., J.W.M., M.R., S.B., K.B., C.P.M., J.A.H., J.S.R., D.S., T.L.B., S.K., J.B.M., J.F.C.); and University of Utah School of Medicine, Salt Lake City, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., S.B., K.B., S.K., J.B.M., J.F.C.)
| | - John F. Carlquist
- From the Intermountain Healthcare (Intermountain Medical Center and LDS and McKay-Dee Hospitals), Murray, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., J.W.M., M.R., S.B., K.B., C.P.M., J.A.H., J.S.R., D.S., T.L.B., S.K., J.B.M., J.F.C.); and University of Utah School of Medicine, Salt Lake City, UT (J.L.A., B.D.H., S.M.S., S.C.W., K.M.S., S.B., K.B., S.K., J.B.M., J.F.C.)
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Horne BD, Lenzini PA, Wadelius M, Jorgensen AL, Kimmel SE, Ridker PM, Eriksson N, Anderson JL, Pirmohamed M, Limdi NA, Pendleton RC, McMillin GA, Burmester JK, Kurnik D, Stein CM, Caldwell MD, Eby CS, Rane A, Lindh JD, Shin JG, Kim HS, Angchaisuksiri P, Glynn RJ, Kronquist KE, Carlquist JF, Grice GR, Barrack RL, Li J, Gage BF. Pharmacogenetic warfarin dose refinements remain significantly influenced by genetic factors after one week of therapy. Thromb Haemost 2012; 107:232-40. [PMID: 22186998 PMCID: PMC3292349 DOI: 10.1160/th11-06-0388] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 11/04/2011] [Indexed: 01/06/2023]
Abstract
By guiding initial warfarin dose, pharmacogenetic (PGx) algorithms may improve the safety of warfarin initiation. However, once international normalised ratio (INR) response is known, the contribution of PGx to dose refinements is uncertain. This study sought to develop and validate clinical and PGx dosing algorithms for warfarin dose refinement on days 6-11 after therapy initiation. An international sample of 2,022 patients at 13 medical centres on three continents provided clinical, INR, and genetic data at treatment days 6-11 to predict therapeutic warfarin dose. Independent derivation and retrospective validation samples were composed by randomly dividing the population (80%/20%). Prior warfarin doses were weighted by their expected effect on S-warfarin concentrations using an exponential-decay pharmacokinetic model. The INR divided by that "effective" dose constituted a treatment response index . Treatment response index, age, amiodarone, body surface area, warfarin indication, and target INR were associated with dose in the derivation sample. A clinical algorithm based on these factors was remarkably accurate: in the retrospective validation cohort its R(2) was 61.2% and median absolute error (MAE) was 5.0 mg/week. Accuracy and safety was confirmed in a prospective cohort (N=43). CYP2C9 variants and VKORC1-1639 G→A were significant dose predictors in both the derivation and validation samples. In the retrospective validation cohort, the PGx algorithm had: R(2)= 69.1% (p<0.05 vs. clinical algorithm), MAE= 4.7 mg/week. In conclusion, a pharmacogenetic warfarin dose-refinement algorithm based on clinical, INR, and genetic factors can explain at least 69.1% of therapeutic warfarin dose variability after about one week of therapy.
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Affiliation(s)
- Benjamin D Horne
- Cardiovascular Department, Intermountain Medical Center, Salt Lake City, Utah 84107, USA.
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Botton MR, Bandinelli E, Rohde LEP, Amon LC, Hutz MH. Influence of genetic, biological and pharmacological factors on warfarin dose in a Southern Brazilian population of European ancestry. Br J Clin Pharmacol 2011; 72:442-50. [PMID: 21320153 PMCID: PMC3175513 DOI: 10.1111/j.1365-2125.2011.03942.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Accepted: 12/26/2010] [Indexed: 11/28/2022] Open
Abstract
AIMS To investigate the influence of polymorphisms in CYP2C9, VKORC1, CYP4F2 and F2 genes on warfarin dose-response and develop a model including genetic and non-genetic factors for warfarin dose prediction needed for each patient. METHODS A total of 279 patients of European ancestry on warfarin medication were investigated. Genotypes for -1639G>A, 1173C>T, and 3730G>A SNPs in the VKORC1 gene, CYP2C9*2 and CYP2C9*3, 1347C>T in the CYP4F2 gene and 494C>T in the F2 gene were determined by allelic discrimination with Taqman 5'-nuclease assays. RESULTS The CYP2C9*2 and CYP2C9*3 polymorphisms in the CYP2C9 gene, -1639G>A and 1173C>T in the VKORC1 gene and 494C>T in the F2 gene are responsible for lower anticoagulant doses. In contrast, 1347C>T in the CYP4F2 gene and 3730G>A in the VKORC1 gene are responsible for higher doses of warfarin. An algorithm including genetic, biological and pharmacological factors that explains 63.3% of warfarin dose variation was developed. CONCLUSION The model suggested has one of the highest coefficients of determination among those described in the literature.
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Howard R, Leathart JBS, French DJ, Krishan E, Kohnke H, Wadelius M, van Schie R, Verhoef T, Maitland-van der Zee AH, Daly AK, Barallon R. Genotyping for CYP2C9 and VKORC1 alleles by a novel point of care assay with HyBeacon® probes. Clin Chim Acta 2011; 412:2063-9. [PMID: 21827742 DOI: 10.1016/j.cca.2011.07.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Accepted: 07/09/2011] [Indexed: 02/03/2023]
Abstract
BACKGROUND Coumarin anticoagulants such as warfarin are used to treat and prevent thromboembolic events in patients. The required dosage is difficult to predict and the risk of over or under anticoagulation are dependent on several environmental and clinical factors, such as concurrent medication, diet, age and genotype for polymorphisms in two genes CYP2C9 and VKORC1. METHODS A novel fluorescent PCR genotyping assay using HyBeacon® probes, was developed to enable clinical staff to genotype the CYP2C9*2 and CYP2C9*3 alleles and the VKORC1 G-1639A polymorphism directly from unextracted blood samples. A prototype PCR instrument, Genie 1, suitable for point of care use was developed to carry out the assays. The panel of tests was validated by analysing blood samples from 156 individuals and comparing genotypes with data obtained using DNA samples from the same individuals. The accuracy of genotypes obtained with the Genie 1 was compared against results from well validated real time PCR and PCR-restriction fragment length polymorphism analysis. RESULTS Identical results were obtained for the newly developed HyBeacon® method and the validation method in all cases except for one where no result was obtained for the VKORC1 polymorphism on the Genie instrument. The samples used for validation represented all six possible *2 and *3 allele-related CYP2C9 genotypes and all three VKORC1 G-1639A genotypes. CONCLUSIONS We observed excellent accuracy for the newly developed method which can determine genotype in less than 2 h.
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Nathisuwan S, Dilokthornsakul P, Chaiyakunapruk N, Morarai T, Yodting T, Piriyachananusorn N. Assessing evidence of interaction between smoking and warfarin: a systematic review and meta-analysis. Chest 2011; 139:1130-1139. [PMID: 21540214 DOI: 10.1378/chest.10-0777] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Chronic smoking, theoretically, can interfere with warfarin metabolism through enzyme-inducing effects of polycyclic aromatic hydrocarbons. However, clinical evidence of interactions between warfarin and smoking are inconclusive. This study aimed to systematically review all relevant clinical evidence of this interaction. METHODS We performed a systematic search using computerized databases, including PubMed, Embase, Cochrane Central Register of Controlled Trials, CINAHL, Allied and Complementary Medicine, PsycINFO, International Pharmaceutical Abstracts, and ClinicalTrials.gov from 1966 to December 2008. Keywords included "warfarin" with "smoking," "tobacco," "cigarette," and "polycyclic aromatic hydrocarbons." Original articles reporting interaction between warfarin and smoking were included. All articles were reviewed independently by two investigators for study design, population, outcomes, and quality of evidence. RESULTS Of the 1,240 studies retrieved, one experimental pharmacokinetic study and 12 cross-sectional studies were included. The pooled analyses of multivariate studies suggested that smoking was associated with a 12.13% (95% CI, 6.999-17.265; P < .001) increase in warfarin dosage requirement and an additional 2.26 mg (95% CI, 2.529-7.042; P = .355) per week compared with nonsmoking. Additional sensitivity analysis of four multivariate studies with adjustment for pharmacogenomic factors suggested that smoking was associated with a 13.21% (95% CI, 8.59%-17.83%; P < .001) increase in warfarin dosage requirement compared with nonsmokers. Results of an experimental pharmacokinetic study lend theoretical support to the findings. CONCLUSIONS Evidence suggests that smoking may potentially cause significant interaction with warfarin by increasing warfarin clearance, which leads to reduced warfarin effects. Close monitoring of warfarin therapy should be instituted when there is a change in smoking status of patients requiring warfarin therapy.
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Affiliation(s)
- Surakit Nathisuwan
- Clinical Pharmacy Division, Department of Pharmacy, Faculty of Pharmacy, Mahidol University, Bangkok, Thailand
| | - Piyameth Dilokthornsakul
- Center of Pharmaceutical Outcomes Research, Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok, Thailand; Department of Pharmacy Practice, Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok, Thailand
| | - Nathorn Chaiyakunapruk
- Center of Pharmaceutical Outcomes Research, Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok, Thailand; Department of Pharmacy Practice, Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok, Thailand; School of Population Health, University of Queensland, Brisbane, QLD, Australia; School of Pharmacy, University of Wisconsin, Madison, WI.
| | - Tatiya Morarai
- Department of Pharmacy Practice, Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok, Thailand
| | - Thararat Yodting
- Department of Pharmacy Practice, Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok, Thailand
| | - Nichakorn Piriyachananusorn
- Department of Pharmacy Practice, Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok, Thailand
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Finkelman BS, Gage BF, Johnson JA, Brensinger CM, Kimmel SE. Genetic warfarin dosing: tables versus algorithms. J Am Coll Cardiol 2011; 57:612-8. [PMID: 21272753 DOI: 10.1016/j.jacc.2010.08.643] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 07/16/2010] [Accepted: 08/24/2010] [Indexed: 01/21/2023]
Abstract
OBJECTIVES The aim of this study was to compare the accuracy of genetic tables and formal pharmacogenetic algorithms for warfarin dosing. BACKGROUND Pharmacogenetic algorithms based on regression equations can predict warfarin dose, but they require detailed mathematical calculations. A simpler alternative, recently added to the warfarin label by the U.S. Food and Drug Administration, is to use genotype-stratified tables to estimate warfarin dose. This table may potentially increase the use of pharmacogenetic warfarin dosing in clinical practice; however, its accuracy has not been quantified. METHODS A retrospective cohort study of 1,378 patients from 3 anticoagulation centers was conducted. Inclusion criteria were stable therapeutic warfarin dose and complete genetic and clinical data. Five dose prediction methods were compared: 2 methods using only clinical information (empiric 5 mg/day dosing and a formal clinical algorithm), 2 genetic tables (the new warfarin label table and a table based on mean dose stratified by genotype), and 1 formal pharmacogenetic algorithm, using both clinical and genetic information. For each method, the proportion of patients whose predicted doses were within 20% of their actual therapeutic doses was determined. Dosing methods were compared using McNemar's chi-square test. RESULTS Warfarin dose prediction was significantly more accurate (all p < 0.001) with the pharmacogenetic algorithm (52%) than with all other methods: empiric dosing (37%; odds ratio [OR]: 2.2), clinical algorithm (39%; OR: 2.2), warfarin label (43%; OR: 1.8), and genotype mean dose table (44%; OR: 1.9). CONCLUSIONS Although genetic tables predicted warfarin dose better than empiric dosing, formal pharmacogenetic algorithms were the most accurate.
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Affiliation(s)
- Brian S Finkelman
- Center for Clinical Epidemiology and Biostatistics, Department of Biostatistics and Epidemiology, University of Pennsylvania School of Medicine, Philadelphia, USA
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Mahajan P, Meyer KS, Wall GC, Price HJ. Clinical applications of pharmacogenomics guided warfarin dosing. Int J Clin Pharm 2011; 33:10-9. [PMID: 21365388 DOI: 10.1007/s11096-011-9486-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Accepted: 10/11/2010] [Indexed: 12/26/2022]
Abstract
AIM OF THE REVIEW To assess the state of the literature concerning pharmacogenomic testing in patients requiring vitamin K antagonists, specifically warfarin. METHOD We conducted a literature search of MEDLINE and International Pharmaceutical Abstracts using the following words: warfarin, pharmacogenetic, and pharmacogenomic. The search results were reviewed by the authors and papers concerning pharmacogenomic testing in warfarin dosing were procured and reviewed. Additionally bibliographies of papers procured were also examined for other studies. The authors focused on clinical trials concerning the use of pharmacogenomic testing in warfarin dosing. RESULTS Although numerous studies have demonstrated that a significant portion of warfarin dosing variability can be explained by genetic polymorphisms, few prospective studies have been conducted that examine the integration of this information in practical dosing situations. Those that have, have shown that using pharmacogenomic information improves initial dosing estimates and decreases the need for frequent clinic visits and laboratory testing. Data showing a reduction in serious bleeding events is sparse. Cost-effectiveness analyses have generally shown a small but positive effect with pharmacogenomic testing in patients receiving warfarin. CONCLUSION Several studies have shown that pharmacogenomic testing for warfarin dosing is more accurate that other dosing schemes. Pharmacogenomic testing improves time to a therapeutic international normalized ratio while requiring fewer dosing adjustments. Patients who require higher or lower than usual doses seem to benefit the most. The cost-effectiveness of pharmacogenomic testing as well as preventing of outcomes such as bleeding or thrombosis are not yet elucidated. Pharmacists, especially those in a community setting can play a role in this new technology by educating prescribers and patients concerning pharmacogenomic testing, and by developing and using dosing protocols that incorporate its use.
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Affiliation(s)
- Pramod Mahajan
- College of Pharmacy and Health Sciences, Drake University, 2507 University Ave, Des Moines, IA 50310, USA
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Johnson SW, Henderson S. Genetics of warfarin sensitivity in an emergency department population with thromboembolic. West J Emerg Med 2011; 12:11-6. [PMID: 21691466 PMCID: PMC3088368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Revised: 11/03/2010] [Accepted: 11/10/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Emergency department (ED) patients with venous thromboembolism (VTE) are eventually treated with a standard dose of warfarin despite the fact that a number of patients are known to be sensitive to warfarin and may experience supra-therapeutic INRs and adverse bleeding events. Pharmacogenetics is an emerging field of medical practice that seeks to improve drug safety and efficacy in an individual patient by tailoring treatment to the patient's known genetic makeup. OBJECTIVE To identify patients with risk for warfarin sensitivity among an ED population with VTE and to assess if the warfarin sensitivity mutations were of significant enough prevalence to be of clinical significance in customizing treatment of VTE. We sought in a pilot study to identify if testing for common CYP2C9 and VKORC1 single nucleotide polymorphisms (SNPs) in patients who were likely to begin warfarin treatment was feasible in an ED setting. METHODS A prospective study that identified and enrolled patients presenting to our ED with high clinical suspicion of VTE. Those with high clinical suspicion of VTE were defined as those who had a Doppler ultrasound or computed tomography pulmonary angiography (CTPA) ordered by the primary emergency physician. Blood was taken and processed to ascertain the following SNPs: CYP2C9*2, CYP2C9*3, and VKORC1 3673. RESULTS Of the 194 patients enrolled, 132 (68.0%) had at least one known warfarin sensitivity mutation and 114 (58.8%) had the most clinically significant VKORC1 3673 mutation. CONCLUSION A majority of our patients had at least one mutation associated with the atypical metabolism of warfarin. Over half of our population had the most clinically significant VKORC1 3673 mutation. They would likely benefit from individualized warfarin dosing if ever needing anticoagulation. Our initial pilot study shows that allele frequencies of target warfarin sensitivity SNPs in our patient population are frequent enough to make initiation of personalized warfarin dosing feasible.
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Affiliation(s)
| | - Sean Henderson
- Address for Correspondence: Sean O. Henderson, MD, Department of Emergency Medicine, LAC + USC Medical Center, 1200 N. State Street Room 1011, Los Angeles, CA 90033.
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French B, Joo J, Geller NL, Kimmel SE, Rosenberg Y, Anderson JL, Gage BF, Johnson JA, Ellenberg JH. Statistical design of personalized medicine interventions: the Clarification of Optimal Anticoagulation through Genetics (COAG) trial. Trials 2010; 11:108. [PMID: 21083927 PMCID: PMC3000386 DOI: 10.1186/1745-6215-11-108] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Accepted: 11/17/2010] [Indexed: 11/16/2022] Open
Abstract
Background There is currently much interest in pharmacogenetics: determining variation in genes that regulate drug effects, with a particular emphasis on improving drug safety and efficacy. The ability to determine such variation motivates the application of personalized drug therapies that utilize a patient's genetic makeup to determine a safe and effective drug at the correct dose. To ascertain whether a genotype-guided drug therapy improves patient care, a personalized medicine intervention may be evaluated within the framework of a randomized controlled trial. The statistical design of this type of personalized medicine intervention requires special considerations: the distribution of relevant allelic variants in the study population; and whether the pharmacogenetic intervention is equally effective across subpopulations defined by allelic variants. Methods The statistical design of the Clarification of Optimal Anticoagulation through Genetics (COAG) trial serves as an illustrative example of a personalized medicine intervention that uses each subject's genotype information. The COAG trial is a multicenter, double blind, randomized clinical trial that will compare two approaches to initiation of warfarin therapy: genotype-guided dosing, the initiation of warfarin therapy based on algorithms using clinical information and genotypes for polymorphisms in CYP2C9 and VKORC1; and clinical-guided dosing, the initiation of warfarin therapy based on algorithms using only clinical information. Results We determine an absolute minimum detectable difference of 5.49% based on an assumed 60% population prevalence of zero or multiple genetic variants in either CYP2C9 or VKORC1 and an assumed 15% relative effectiveness of genotype-guided warfarin initiation for those with zero or multiple genetic variants. Thus we calculate a sample size of 1238 to achieve a power level of 80% for the primary outcome. We show that reasonable departures from these assumptions may decrease statistical power to 65%. Conclusions In a personalized medicine intervention, the minimum detectable difference used in sample size calculations is not a known quantity, but rather an unknown quantity that depends on the genetic makeup of the subjects enrolled. Given the possible sensitivity of sample size and power calculations to these key assumptions, we recommend that they be monitored during the conduct of a personalized medicine intervention. Trial Registration clinicaltrials.gov: NCT00839657
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Affiliation(s)
- Benjamin French
- Department of Biostatistics and Epidemiology, University of Pennsylvania School of Medicine, 423 Guardian Drive, Philadelphia, Pennsylvania 19104, USA.
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Mahajan P, Meyer KS, Wall GC, Price HJ. Clinical applications of pharmacogenomics guided warfarin dosing. Int J Clin Pharm 2010; 35:359-68. [DOI: 10.1007/s11096-010-9448-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Accepted: 10/11/2010] [Indexed: 12/28/2022]
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