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GERDAN V. Akılcı ilaç kullanımı: Varfarin. Ege Tıp Dergisi 2021. [DOI: 10.19161/etd.863730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Ooi QX, Wright DFB, Isbister GK, Duffull SB. A factor VII-based method for the prediction of anticoagulant response to warfarin. Sci Rep 2018; 8:12041. [PMID: 30104739 PMCID: PMC6089929 DOI: 10.1038/s41598-018-30516-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 07/25/2018] [Indexed: 11/12/2022] Open
Abstract
Warfarin dosing methods based on existing models for warfarin and the international normalised ratio (INR) give biased maintenance dose predictions at the upper and lower quantiles of dose requirements. The aim of this work is to propose a conceptually different approach to predict INR after warfarin dosing. Factor VII concentration was proposed as the principal driving force for the INR. The time to steady-state INR (tSS,INR) was determined based on the INR response to changes in factor VII concentrations following warfarin initiation, and from this the steady-state INR (INRSS) was derived. The proposed method requires timed, paired blood samples of INR and factor VII. At different simulated warfarin dose rates, the prediction error associated with the proposed method was shown to be within clinically acceptable limits for both the tSS,INR (±2 days) and INRSS (±0.2). The use of the method was demonstrated in two patients who were initiated with 5 mg of warfarin daily. The difference in predicted versus actual steady-state INR were 0.0 and −0.4. The proposed method represents a unique approach to predict the INR. It considers factor VII as the main driver for INR and provides valuable information about the time to steady state INR.
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Affiliation(s)
- Qing-Xi Ooi
- School of Pharmacy, University of Otago, Dunedin, New Zealand.
| | | | - Geoffrey K Isbister
- School of Medicine and Public Health, University of Newcastle, Newcastle, New South Wales, Australia
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Saffian SM, Duffull SB, Wright D. Warfarin Dosing Algorithms Underpredict Dose Requirements in Patients Requiring ≥7 mg Daily: A Systematic Review and Meta-analysis. Clin Pharmacol Ther 2017; 102:297-304. [PMID: 28160278 DOI: 10.1002/cpt.649] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 01/26/2017] [Accepted: 01/29/2017] [Indexed: 01/28/2023]
Abstract
There is preliminary evidence to suggest that some published warfarin dosing algorithms produce biased maintenance dose predictions in patients who require higher than average doses. We conducted a meta-analysis of warfarin dosing algorithms to determine if there exists a systematic under- or overprediction of dose requirements for patients requiring ≥7 mg/day across published algorithms. Medline and Embase databases were searched up to September 2015. We quantified the proportion of over- and underpredicted doses in patients whose observed maintenance dose was ≥7 mg/day. The meta-analysis included 47 evaluations of 22 different warfarin dosing algorithms from 16 studies. The meta-analysis included data from 1,492 patients who required warfarin doses of ≥7 mg/day. All 22 algorithms were found to underpredict warfarin dosing requirements in patients who required ≥7 mg/day by an average of 2.3 mg/day with a pooled estimate of underpredicted doses of 92.3% (95% confidence interval 90.3-94.1, I2 = 24%).
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Affiliation(s)
- S M Saffian
- School of Pharmacy, University of Otago, Dunedin, New Zealand.,Faculty of Pharmacy, University Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - S B Duffull
- School of Pharmacy, University of Otago, Dunedin, New Zealand
| | - Dfb Wright
- School of Pharmacy, University of Otago, Dunedin, New Zealand
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Murphy R, Stehli A, Nguyen H, Leu SY, Nguyen DV, Schwarzkopf R. Assessment of Dosing and Patient Factors on the Efficacy of Warfarin Following Total Joint Replacement. Open Orthop J 2015; 9:129-38. [PMID: 26157529 PMCID: PMC4483539 DOI: 10.2174/1874325001509010129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 02/19/2015] [Accepted: 02/28/2015] [Indexed: 11/22/2022] Open
Abstract
The purpose of this study was to determine the percentage of patients discharged with a subtherapeutic INR <1.8 using our institutions inpatient warfarin dosing nomogram following total joint arthroplasty (TJA). We examined predisposing risk factors for a subtherapeutic discharge (INR <1.8), including increased body weight, age, gender, end stage renal disease (ESRD), smoking, and peri-operative transfusion. Chart review identified 249 patients for study inclusion. Logistic regression (LR) was used to identify associated risk factors for a subtherapeutic INR (<1.8) on day of discharge. The majority of patients (58.6%, 146 of 249) following TJA surgery were found to have a subtherapeutic INR level (INR<1.8) at discharge (mean length of stay 2.6 days). Multivariate LR analysis found that weight greater than 180 lbs. (OR 2.08, CI 1.09, 3.98, P=0.027) was found to increase the odds of a subtherapeutic INR on day of discharge. Our results were not significant for weight 20% beyond ideal body weight, age (>65y), gender, peri-operative transfusion, smoking, ESRD or autoimmune disease. A patient’s body weight influences response to warfarin following TJA. An inpatient warfarin dosing nomogram that takes into account a patient’s weight should be used to reduce the risk of subtherapeutic INR levels in obese TJA patients.
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Affiliation(s)
- Ryan Murphy
- Department of Orthopaedic Surgery, University of California, Irvine School of Medicine, USA
| | - Annamarie Stehli
- Institute for Clinical and Translational Science, University of California, Irvine, CA 92687, USA
| | - Hiep Nguyen
- Inpatient Pharmacy, University of California, Irvine Medical Center, USA
| | - Szu-Yun Leu
- Institute for Clinical and Translational Science, University of California, Irvine, CA 92687, USA ; Department of Pediatrics, University of California, Irvine School of Medicine, USA
| | - Danh V Nguyen
- Institute for Clinical and Translational Science, University of California, Irvine, CA 92687, USA ; Department of Medicine, University of California Irvine, Orange, CA 92868, USA
| | - Ran Schwarzkopf
- Department of Orthopaedic Surgery, University of California, Irvine School of Medicine, USA
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Šupe S, Božina N, Matijević V, Bazina A, Mišmaš A, Ljevak J, Alvir D, Habek M, Poljaković Z. Prevalence of genetic polymorphisms of CYP2C9 and VKORC1 — Implications for warfarin management and outcome in Croatian patients with acute stroke. J Neurol Sci 2014; 343:30-5. [DOI: 10.1016/j.jns.2014.04.039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 04/23/2014] [Accepted: 04/27/2014] [Indexed: 10/25/2022]
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Johnson EG, Horne BD, Carlquist JF, Anderson JL. Genotype-Based Dosing Algorithms for Warfarin Therapy: Data Review and Recommendations. Mol Diagn Ther 2011; 15:255-64. [DOI: 10.1007/bf03256417] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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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. Pharmacogenomics J 2012; 12:417-24. [PMID: 21606949 DOI: 10.1038/tpj.2011.18] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [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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Abstract
Warfarin has long been the mainstay of oral anticoagulation therapy for the treatment and prevention of venous and arterial thrombosis. The narrow therapeutic index of warfarin, and the complex number of factors that influence international normalized ratio (INR) response, makes optimization of warfarin therapy challenging. Determination of the appropriate warfarin dose during initiation and maintenance therapy requires an understanding of patient factors that influence dose response: age, body weight, nutritional status, acute and chronic disease states, and changes in concomitant drug therapy and diet. This review will examine specific clinical factors that can affect the pharmacokinetics and pharmacodynamics of warfarin, as well as the role of pharmacogenetics in optimizing warfarin therapy.
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Affiliation(s)
- Pamela J. White
- Pharmacy Clinical Specialist, Legacy Health Anticoagulation Clinics, Portland, OR, USA
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Pendleton RC, Wheeler M, Wanner N, Strong MB, Vinik R, Peters CL. A safe, effective, and easy to use warfarin initiation dosing nomogram for post-joint arthroplasty patients. J Arthroplasty 2010; 25:121-7. [PMID: 19062248 DOI: 10.1016/j.arth.2008.09.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Accepted: 09/21/2008] [Indexed: 02/01/2023] Open
Abstract
Venous thromboembolism (VTE) is a complication after joint arthroplasty, and pharmacologic prophylaxis is recommended to reduce this risk. Warfarin is often used, but initial dosing and management can be difficult. We studied a single-center prospective cohort of consecutive (n = 351) post-joint arthroplasty/revision patients who were initiated on warfarin using a new initiation nomogram and then discharged to home with home health services. The mean time to an international normalized ratio (INR) of 2.0 or higher was 5 days, with a mean INR of 2.1 on the fifth postoperative day. Two patients (0.6%) had an INR higher than 5 in the first 10 days of therapy. Adverse events were uncommon: 4 patients (1.14%) had VTE, 1 had major bleeding episode, and 6 patients (1.7%) had minor bleeding. A specific warfarin dosing nomogram managed by an anticoagulation service and used in joint arthroplasty/revision patients who are discharged to home with home health services leads to effective anticoagulation with few associated adverse events.
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Affiliation(s)
- Robert C Pendleton
- Department of Medicine, General Internal Medicine, University Healthcare Thrombosis Service, University of Utah, Salt Lake City, Utah 84132, USA
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Ferder NS, Eby CS, Deych E, Harris JK, Ridker PM, Milligan PE, Goldhaber SZ, King CR, Giri T, McLeod HL, Glynn RJ, Gage BF. Ability of VKORC1 and CYP2C9 to predict therapeutic warfarin dose during the initial weeks of therapy. J Thromb Haemost 2010; 8:95-100. [PMID: 19874474 PMCID: PMC3718044 DOI: 10.1111/j.1538-7836.2009.03677.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND CYP2C9 and VKORC1 genotypes predict therapeutic warfarin dose at initiation of therapy; however, the predictive ability of genetic information after a week or longer is unknown. Experts have hypothesized that genotype becomes irrelevant once international normalized ratio (INR) values are available because INR response reflects warfarin sensitivity. METHODS We genotyped the participants in the Prevention of Recurrent Venous Thromboembolism (PREVENT) trial, who had idiopathic venous thromboemboli and began low-intensity warfarin (therapeutic INR 1.5-2.0) using a standard dosing protocol. To develop pharmacogenetic models, we quantified the effect of genotypes, clinical factors, previous doses and INR on therapeutic warfarin dose in the 223 PREVENT participants who were randomized to warfarin and achieved stable therapeutic INRs. RESULTS A pharmacogenetic model using data from day 0 (before therapy initiation) explained 54% of the variability in therapeutic dose (R(2)). The R(2) increased to 68% at day 7, 75% at day 14, and 77% at day 21, because of increasing contributions from prior doses and INR response. Although CYP2C9 and VKORC1 genotypes were significant independent predictors of therapeutic dose at each weekly interval, the magnitude of their predictive ability diminished over time: partial R(2) of genotype was 43% at day 0, 12% at day 7, 4% at day 14, and 1% at day 21. CONCLUSION Over the first weeks of warfarin therapy, INR and prior dose become increasingly predictive of therapeutic dose, and genotype becomes less relevant. However, at day 7, genotype remains clinically relevant, accounting for 12% of therapeutic dose variability.
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Affiliation(s)
- N S Ferder
- Saint Louis College of Pharmacy, St Louis, MO, USA
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Lazo-Langner A, Monkman K, Kovacs MJ. Predicting warfarin maintenance dose in patients with venous thromboembolism based on the response to a standardized warfarin initiation nomogram. J Thromb Haemost 2009; 7:1276-83. [PMID: 19453939 DOI: 10.1111/j.1538-7836.2009.03483.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND Polymorphisms in the VKORC1 and CYP2C9 genes influence warfarin requirements. It has been suggested that dosing algorithms incorporating them might outperform usual care. Standardized warfarin initiation nomograms are safe and effective and patients' responses to them could be used to predict warfarin requirements without the need for genetic testing. OBJECTIVES To develop a model to predict warfarin dose requirements based on the response to a standard nomogram without using genetic testing. PATIENTS/METHODS We included 363 outpatients with acute venous thromboembolism who were started on treatment using a standardized warfarin nomogram and achieved a stable maintenance warfarin dose defined as a dose prescribed twice consecutively after two consecutive INR measurements between 2.0 and 3.0. Linear regression was used to derive equations predicting the maintenance dose and models were validated using non-parametric bootstrapping and tested in an independent cohort. RESULTS Three models were constructed for patients completing the nomogram until day 3 (warfarin dose (mg week(-1)) = Exp [2.737 + 1.896(INR(3)(-1))-0.008(Age)]; R2adj = 0.462), day 5 (warfarin dose (mg week(-1)) = Exp[2.261 + 2.412(INR(3)(-1)) -0.285(DeltaINR(5-3))]; R2adj = 0.603) and day 8 (warfarin dose (mg week(-1)) = Exp[1.574 + 1.788(INR(8)(-1)) + 0.024(cumulated warfarin dose until nomogram day 7)]; R2adj = 0.643), where Exp is the exponential function; INR3 and INR8 are the INR on days 3 or 8 of the nomogram, and DeltaINR(5-3) is the difference in the INR on days 5 and 3. All models were internally and externally validated and were accurate to within 25% of the actual dose in >60% of patients. CONCLUSION Maintenance warfarin dose can be accurately predicted using individual response to a standard warfarin initiation nomogram without the need for costly genetic testing.
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Affiliation(s)
- A Lazo-Langner
- Division of Hematology, Department of Medicine, University of Western Ontario, London, ON, Canada
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Lenzini PA, Grice GR, Milligan PE, Dowd MB, Subherwal S, Deych E, Eby CS, King CR, Porche-Sorbet RM, Murphy CV, Marchand R, Millican EA, Barrack RL, Clohisy JC, Kronquist K, Gatchel SK, Gage BF. Laboratory and clinical outcomes of pharmacogenetic vs. clinical protocols for warfarin initiation in orthopedic patients. J Thromb Haemost 2008; 6:1655-62. [PMID: 18662264 PMCID: PMC2920450 DOI: 10.1111/j.1538-7836.2008.03095.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
BACKGROUND Warfarin is commonly prescribed for prophylaxis and treatment of thromboembolism after orthopedic surgery. During warfarin initiation, out-of-range International Normalized Ratio (INR) values and adverse events are common. METHODS In orthopedic patients beginning warfarin therapy, we developed and prospectively validated pharmacogenetic and clinical dose refinement algorithms to revise the estimated therapeutic dose after 4 days of therapy. RESULTS The pharmacogenetic algorithm used the cytochrome P450 (CYP) 2C9 genotype, smoking status, peri-operative blood loss, liver disease, INR values and dose history to predict the therapeutic dose. The R(2) was 82% in a derivation cohort (n = 86) and 70% when used prospectively (n = 146). The R(2) of the clinical algorithm that used INR values and dose history to predict the therapeutic dose was 57% in a derivation cohort (n = 178) and 48% in a prospective validation cohort (n = 146). In 1 month of prospective follow-up, the percent time spent in the therapeutic range was 7% higher (95% CI: 2.7-11.7) in the pharmacogenetic cohort. The risk of a laboratory or clinical adverse event was also significantly reduced in the pharmacogenetic cohort (Hazard Ratio 0.54; 95% CI: 0.30-0.97). CONCLUSIONS Warfarin dose adjustments that incorporate genotype and clinical variables available after four warfarin doses are accurate. In this non-randomized, prospective study, pharmacogenetic dose refinements were associated with more time spent in the therapeutic range and fewer laboratory or clinical adverse events. To facilitate gene-guided warfarin dosing we created a non-profit website, http://www.WarfarinDosing.org.
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Affiliation(s)
- Petra A. Lenzini
- Washington University School of Medicine, Department of Internal Medicine
| | - Gloria R. Grice
- Washington University School of Medicine, Department of Internal Medicine
- St. Louis College of Pharmacy
| | - Paul E. Milligan
- Washington University School of Medicine, Department of Internal Medicine
- St. Louis College of Pharmacy
| | | | - Sumeet Subherwal
- Washington University School of Medicine, Department of Internal Medicine
| | - Elena Deych
- Washington University School of Medicine, Department of Internal Medicine
| | - Charles S. Eby
- Washington University School of Medicine, Department of Pathology
| | - Cristi R. King
- Washington University School of Medicine, Department of Internal Medicine
| | | | | | | | - Eric A. Millican
- Washington University School of Medicine, Department of Internal Medicine
| | - Robert L. Barrack
- Washington University School of Medicine, Department of Orthopedic Surgery
| | - John C. Clohisy
- Washington University School of Medicine, Department of Orthopedic Surgery
| | | | - Susan K. Gatchel
- Washington University School of Medicine, Department of Internal Medicine
| | - Brian F. Gage
- Washington University School of Medicine, Department of Internal Medicine
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Gage BF, Eby C, Johnson JA, Deych E, Rieder MJ, Ridker PM, Milligan PE, Grice G, Lenzini P, Rettie AE, Aquilante CL, Grosso L, Marsh S, Langaee T, Farnett LE, Voora D, Veenstra DL, Glynn RJ, Barrett A, McLeod HL. Use of pharmacogenetic and clinical factors to predict the therapeutic dose of warfarin. Clin Pharmacol Ther 2008; 84:326-31. [PMID: 18305455 PMCID: PMC2683977 DOI: 10.1038/clpt.2008.10] [Citation(s) in RCA: 584] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Initiation of warfarin therapy using trial-and-error dosing is problematic. Our goal was to develop and validate a pharmacogenetic algorithm. In the derivation cohort of 1,015 participants, the independent predictors of therapeutic dose were: VKORC1 polymorphism -1639/3673 G>A (-28% per allele), body surface area (BSA) (+11% per 0.25 m(2)), CYP2C9(*)3 (-33% per allele), CYP2C9(*)2 (-19% per allele), age (-7% per decade), target international normalized ratio (INR) (+11% per 0.5 unit increase), amiodarone use (-22%), smoker status (+10%), race (-9%), and current thrombosis (+7%). This pharmacogenetic equation explained 53-54% of the variability in the warfarin dose in the derivation and validation (N= 292) cohorts. For comparison, a clinical equation explained only 17-22% of the dose variability (P < 0.001). In the validation cohort, we prospectively used the pharmacogenetic-dosing algorithm in patients initiating warfarin therapy, two of whom had a major hemorrhage. To facilitate use of these pharmacogenetic and clinical algorithms, we developed a nonprofit website, http://www.WarfarinDosing.org.
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Affiliation(s)
- B F Gage
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA.
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Pharmacogenetic-Based Dosing of Warfarin. Obstet Gynecol 2008; 112:692-693. [DOI: 10.1097/01.aog.0000326888.48420.03] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Affiliation(s)
- S M Thacker
- St Louis College of Pharmacy, St Louis, MO, USA
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Abstract
Evaluation of: Anderson JL, Horne BD, Stevens SM et al.: Randomized trial of genotype-guided versus standard warfarin dosing in patients initiating oral anticoagulation. Circulation 116, 2563–2570 (2007). Warfarin is an effective oral anticoagulant used to treat or prevent thromboembolic disorders in millions of patients worldwide. Even with conscientious International Normalized Ratio (INR) monitoring, warfarin initiation carries a high risk of hemorrhage. Pharmacogenetic studies have determined that variants in the CYP2C9 and VKORC1 genes help to predict the therapeutic warfarin dose. Whether using this information prospectively will prevent under- and over-dosing of warfarin is unknown. To answer this question, the Couma-Gen investigators randomized half of a 200-patient cohort beginning warfarin therapy to clinical dosing and half to pharmacogenetic dosing. Overall, pharmacogenetic dosing slightly increased time in the therapeutic INR range (p = not significant) and decreased the number of INR tests required. The trial has important implications for the new NIH-funded multicentered trial. Here, we discuss the Couma-Gen study and its implications for the design, randomization, blinding and end point definition of future studies.
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Affiliation(s)
- Lawrence J Lesko
- Food and Drug Administration, Office of Clinical Pharmacology, Center for Drug Evaluation and Research, Silver Spring, MD 20993, USA
| | - Brian F Gage
- Washington University School of Medicine in St Louis, Division of General Medical Sciences, Department of Medicine, St Louis, MO 63110, USA
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Grice GR, Milligan PE, Eby C, Gage BF. Pharmacogenetic dose refinement prevents warfarin overdose in a patient who is highly warfarin-sensitive. J Thromb Haemost 2008; 6:207-9. [PMID: 17944998 DOI: 10.1111/j.1538-7836.2007.02797.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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