Atrial FibrillationWARFPGXNCT00904293
Genotype-Guided Warfarin Therapy Trial
A study testing Genotype-guided dose determination and Non-genotype guided warfarin dosing in people with Atrial Fibrillation and Deep Vein Thrombosis, run by University of North Carolina, Chapel Hill at 1 site in United States.
Trial summary
The purpose of the investigators' study is to determine the clinical utility of a warfarin-dosing algorithm that incorporates genetic information (VKORC1 and CYP2C9 alleles) for adult patients initiating warfarin therapy. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Atrial Fibrillation, Deep Vein Thrombosis, Pulmonary Embolism
- What is being tested?
- Genotype-guided dose determination and Non-genotype guided warfarin dosing
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 109 participants
- Where
- 1 siteUnited States
- Study dates
- Aug 2008to Jan 2012
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Adults ≥18 years old
- Patients who are beginning warfarin for a variety of diseases or conditions that require long-term oral anticoagulation with target INR > 2.0 for at least 3 months
- Subjects that will be following up in UNC anticoagulation clinics at the Ambulatory Care Center or the Family Medicine Center
Who cannot join
- Patients who are unable to complete the study materials (questionnaires) with or without assistance (for example, those with dementia)
- Non-English speaking patients
- Patients who are being started on anticoagulation intended to last < 3 months or whose target INR is < 2.0
- Patients who have a history of treatment with warfarin and a known dose requirement will be excluded (as they should be restarted on the previous dose)
- Pregnant women will be excluded because warfarin is a teratogen and pregnant women should not take the medication
- Patients will also be excluded if their treating physician does not agree to use the recommended INR dose or feels that the patient should not be enrolled in the study
Trial locations and contacts
1 site in 1 country.
United States1 site
UNC Hospitals, UNC Anticoagulation Clinic at the Ambulatory Care Center (ACC), UNC Family Medicine Center Anti-coagulation Clinic
Chapel Hill, North Carolina, 27599
About this study
Official title: Randomized Controlled Trial of Genotype-Guided Dosing of Warfarin Therapy
The purpose of the investigators' study is to determine the clinical utility of a warfarin-dosing algorithm that incorporates genetic information (VKORC1 and CYP2C9 alleles) for adult patients initiating warfarin therapy.
Read the detailed description
Almost 20 million prescriptions are written for warfarin each year in the US and yet it is one of the most problematic drugs in the modern medical formulary. Warfarin has a narrow therapeutic window and the hemorrhagic or thrombotic implications of modest over- or under-dosing can be devastating. Warfarin is one of the leading causes of emergency department visits and hospitalizations due to adverse drug events worldwide. Adverse events from warfarin are more common during the initial months of treatment before the optimal dose is determined. Moreover, there is substantial individual variation in response to warfarin necessitating frequent monitoring and dosage adjustments. The monitoring and dosing of warfarin is so problematic that many primary care physicians have abdicated this role to specialized "warfarin clinics" which are devoted solely to following patients on this agent. Unfortunately, no good alternatives to warfarin exist for the common indications requiring chronic anticoagulation such as atrial fibrillation, deep vein thrombosis, pulmonary embolism, and artificial heart valves.
Pharmacogenomics offers substantial hope for improved care of patients taking warfarin. One group estimated that formally integrating genetic testing into routine warfarin therapy in the US could result in the avoidance of 85,000 serious bleeding events and 17,000 strokes annually with a cost savings of over $1 billion annually. Common single nucleotide polymorphisms (SNPs) in the gene encoding Vitamin K Epoxide Reductase (VKOR) substantially affect one's sensitivity to warfarin, mediating a doubling or halving of the dose required for optimal anticoagulation. Warfarin inhibits clotting by inhibiting the enzyme VKOR, and thus inhibiting vitamin K dependent clotting factors. A number of recent retrospective studies have shown that polymorphisms in the VKOR gene may account for 20-30% of the variance in warfarin dose seen in patients on stable, long-term warfarin therapy.
Another genetic determinant of variance in warfarin dose is the cytochrome p450 2C9 enzyme CYP2C9. It is almost wholly responsible for metabolism of the more active S-enantiomer of warfarin. The 2C9*2 and 2C9*3 polymorphisms in the CYP2C9 gene are associated with reduced warfarin metabolism, and a number of retrospective studies have shown that these polymorphisms may account for 10-15% of the variance in warfarin dosage in patients on stable, long-term warfarin therapy. In addition, the variant CYP2C9 alleles have been associated with longer times to stabilization of INR and a higher risk for bleeding events. These polymorphisms are seen in ~20-30% of the Caucasian population, but are rare in African Americans and Asians. Together, known VKOR and CYP2C9 variants may account for 40% of the variability in warfarin dosing.
By combining clinical information such as weight, height, and concomitant medications with VKOR and CYP2C9 genotypic information, several algorithms have been devised that calculate warfarin doses. These algorithms have been shown to accurately predict warfarin doses in retrospective studies of patients already on long-term stable warfarin doses. Some small, pilot studies in orthopedic patients suggest that prospective genetic-based dosing is feasible and may result in achieving stable doses sooner in patients with certain genetic variants. However, the prospective studies are small, pilot studies limited to orthopedic patients that did not include medical patients with common indications requiring chronic oral anticoagulation. They are also limited by study designs that include only historical controls. No RCTs have been reported in the literature and further evaluation is needed to determine the utility and cost-effectiveness of genetic-based algorithms. The NHLBI is planning a double-blind, randomized three-arm trial, but the trial will not begin enrolling subjects until 2008 at the earliest and data analysis and dissemination is planned to begin beyond 2011.
- Being tested
- Genotype-guided dose determination, Non-genotype guided warfarin dosing
- Keywords
- warfarin, CYP2C9, VKOR, Coumadin, pharmacogenetics, pharmacogenomics, anticoagulation, genotype-guided therapy
- Medical subject headings
- Atrial Fibrillation, Venous Thrombosis, Pulmonary Embolism
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Genotype-guided dose determinationOther
Patients in both arms will be treated with warfarin. Those in the experimental group will have initial doses determined using an algorithm (from www.warfarindosing.org) incorporating genetic and clinical factors. Those in the control group will have doses determined using the same algorithm, but without including the genetic factors.
Non-genotype guided warfarin dosingOther
Those in the control group will have doses determined using the same algorithm, but without including the genetic factors.
| Study group | Role | What they receive |
|---|---|---|
| Genotype-guided warfarin dosing | Experimental | A dosing algorithm including clinical factors and genotype information (VKORC1 and CYP2C9) will be used to determine initial warfarin doses. Receives: Other: Genotype-guided dose determination |
| Non-genotype guided warfarin dosing | Active comparator | Initial warfarin dosing will be determined using the same algorithm as in the experimental group, but only including the clinical factors and not including the genotype information Receives: Other: Non-genotype guided warfarin dosing |
What is being measured
The primary outcome is the main question the study is designed to answer.
Time in therapeutic range (TTR)
Measured: 3 months
Number of anticoagulation visits
Measured: 3 months
Secondary outcomes (9)
Proportion of INRs > 4
Measured: 3 months
Major bleeding events
Measured: 3 months
Minor bleeding events
Measured: 3 months
Thromboembolic complications
Measured: 3 months
All-cause mortality
Measured: 3 months
Time to therapeutic dose
Measured: 3 months
Emergency department visits
Measured: 3 months
Hospitalizations
Measured: 3 months
Costs and cost-effectiveness
Measured: 3 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted19 May 2009 (estimated)
- Study startAug 2008
- Primary completionJan 2012
- Study completionJan 2012
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (9)Papers the sponsor has linked to this study.
- Other trials for Atrial FibrillationStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind
- Who is masked
- Participant, Care provider
- Enrolment
- 109 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of North Carolina, Chapel Hill
- Sponsor type
- University, hospital or other
- Collaborators
- UNC Institute for Pharmacogenomics and Individualized Therapy
- Responsible party
- Sponsor
- Investigators
- Daniel E Jonas, MD, MPH, Principal investigator, UNC Institute for Pharmacogenomics and Individualized Therapy
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT00904293
- Sponsor's protocol ID
- 07-1644
- Acronym
- WARFPGX
- Status last verified
- Oct 2013
- First submitted
- 6 Apr 2009
- Last updated
- 6 May 2016
- Results posted
- No
- Data monitoring committee
- No
Publications
Levine MN, Raskob G, Landefeld S, Kearon C. Hemorrhagic complications of anticoagulant treatment. Chest. 2001 Jan;119(1 Suppl):108S-121S. doi: 10.1378/chest.119.1_suppl.108s.
PubMed 11157645Hafner JW Jr, Belknap SM, Squillante MD, Bucheit KA. Adverse drug events in emergency department patients. Ann Emerg Med. 2002 Mar;39(3):258-67. doi: 10.1067/mem.2002.121401.
PubMed 11867978McWilliam A, Lutter R, Nardinelli C. Jointcenter; AEI-Brookings Joint Center For Regulatory Studies. Working Paper 06-23, November 2006
Rieder MJ, Reiner AP, Gage BF, Nickerson DA, Eby CS, McLeod HL, Blough DK, Thummel KE, Veenstra DL, Rettie AE. Effect of VKORC1 haplotypes on transcriptional regulation and warfarin dose. N Engl J Med. 2005 Jun 2;352(22):2285-93. doi: 10.1056/NEJMoa044503.
PubMed 15930419Li T, Lange LA, Li X, Susswein L, Bryant B, Malone R, Lange EM, Huang TY, Stafford DW, Evans JP. Polymorphisms in the VKORC1 gene are strongly associated with warfarin dosage requirements in patients receiving anticoagulation. J Med Genet. 2006 Sep;43(9):740-4. doi: 10.1136/jmg.2005.040410. Epub 2006 Apr 12.
PubMed 16611750Sconce EA, Khan TI, Wynne HA, Avery P, Monkhouse L, King BP, Wood P, Kesteven P, Daly AK, Kamali F. The impact of CYP2C9 and VKORC1 genetic polymorphism and patient characteristics upon warfarin dose requirements: proposal for a new dosing regimen. Blood. 2005 Oct 1;106(7):2329-33. doi: 10.1182/blood-2005-03-1108. Epub 2005 Jun 9.
PubMed 15947090Millican, E., et al. Blood, Epub ahead of print, Mar 26, 2007
Voora D, Eby C, Linder MW, Milligan PE, Bukaveckas BL, McLeod HL, Maloney W, Clohisy J, Burnett RS, Grosso L, Gatchel SK, Gage BF. Prospective dosing of warfarin based on cytochrome P-450 2C9 genotype. Thromb Haemost. 2005 Apr;93(4):700-5. doi: 10.1160/TH04-08-0542.
PubMed 15841315Jonas DE, Evans JP, McLeod HL, Brode S, Lange LA, Young ML, Shilliday BB, Bardsley MM, Swinton-Jenkins NJ, Weck KE. Impact of genotype-guided dosing on anticoagulation visits for adults starting warfarin: a randomized controlled trial. Pharmacogenomics. 2013 Oct;14(13):1593-603. doi: 10.2217/pgs.13.145.
PubMed 24088130
Study at a glance
From the registry record, last updated by the sponsor on 6 May 2016. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Randomized Controlled Trial of Genotype-Guided Dosing of Warfarin Therapy
- ClinicalTrials.gov ID
- NCT00904293
- Acronym / sponsor ID
- WARFPGX / 07-1644
- Keywords
- warfarin, CYP2C9, VKOR, Coumadin, pharmacogenetics, pharmacogenomics, anticoagulation, genotype-guided therapy
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 109 participants (actual)
- Lead sponsor
- University of North Carolina, Chapel HillUniversity, hospital or other
- Collaborators
- UNC Institute for Pharmacogenomics and Individualized Therapy
- Study start
- Aug 2008
- Primary completion
- Jan 2012 (actual)
- Study completion
- Jan 2012 (actual)
- First posted
- 19 May 2009 (estimated)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of the investigators' study is to determine the clinical utility of a warfarin-dosing algorithm that incorporates genetic information (VKORC1 and CYP2C9 alleles) for adult patients initiating warfarin therapy.
Detailed description
Almost 20 million prescriptions are written for warfarin each year in the US and yet it is one of the most problematic drugs in the modern medical formulary. Warfarin has a narrow therapeutic window and the hemorrhagic or thrombotic implications of modest over- or under-dosing can be devastating. Warfarin is one of the leading causes of emergency department visits and hospitalizations due to adverse drug events worldwide. Adverse events from warfarin are more common during the initial months of treatment before the optimal dose is determined. Moreover, there is substantial individual variation in response to warfarin necessitating frequent monitoring and dosage adjustments. The monitoring and dosing of warfarin is so problematic that many primary care physicians have abdicated this role to specialized "warfarin clinics" which are devoted solely to following patients on this agent. Unfortunately, no good alternatives to warfarin exist for the common indications requiring chronic anticoagulation such as atrial fibrillation, deep vein thrombosis, pulmonary embolism, and artificial heart valves.
Pharmacogenomics offers substantial hope for improved care of patients taking warfarin. One group estimated that formally integrating genetic testing into routine warfarin therapy in the US could result in the avoidance of 85,000 serious bleeding events and 17,000 strokes annually with a cost savings of over $1 billion annually. Common single nucleotide polymorphisms (SNPs) in the gene encoding Vitamin K Epoxide Reductase (VKOR) substantially affect one's sensitivity to warfarin, mediating a doubling or halving of the dose required for optimal anticoagulation. Warfarin inhibits clotting by inhibiting the enzyme VKOR, and thus inhibiting vitamin K dependent clotting factors. A number of recent retrospective studies have shown that polymorphisms in the VKOR gene may account for 20-30% of the variance in warfarin dose seen in patients on stable, long-term warfarin therapy.
Another genetic determinant of variance in warfarin dose is the cytochrome p450 2C9 enzyme CYP2C9. It is almost wholly responsible for metabolism of the more active S-enantiomer of warfarin. The 2C9*2 and 2C9*3 polymorphisms in the CYP2C9 gene are associated with reduced warfarin metabolism, and a number of retrospective studies have shown that these polymorphisms may account for 10-15% of the variance in warfarin dosage in patients on stable, long-term warfarin therapy. In addition, the variant CYP2C9 alleles have been associated with longer times to stabilization of INR and a higher risk for bleeding events. These polymorphisms are seen in ~20-30% of the Caucasian population, but are rare in African Americans and Asians. Together, known VKOR and CYP2C9 variants may account for 40% of the variability in warfarin dosing.
By combining clinical information such as weight, height, and concomitant medications with VKOR and CYP2C9 genotypic information, several algorithms have been devised that calculate warfarin doses. These algorithms have been shown to accurately predict warfarin doses in retrospective studies of patients already on long-term stable warfarin doses. Some small, pilot studies in orthopedic patients suggest that prospective genetic-based dosing is feasible and may result in achieving stable doses sooner in patients with certain genetic variants. However, the prospective studies are small, pilot studies limited to orthopedic patients that did not include medical patients with common indications requiring chronic oral anticoagulation. They are also limited by study designs that include only historical controls. No RCTs have been reported in the literature and further evaluation is needed to determine the utility and cost-effectiveness of genetic-based algorithms. The NHLBI is planning a double-blind, randomized three-arm trial, but the trial will not begin enrolling subjects until 2008 at the earliest and data analysis and dissemination is planned to begin beyond 2011.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, care provider)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Genotype-guided warfarin dosing | Experimental | Other: Genotype-guided dose determinationA dosing algorithm including clinical factors and genotype information (VKORC1 and CYP2C9) will be used to determine initial warfarin doses. |
| Non-genotype guided warfarin dosing | Active comparator | Other: Non-genotype guided warfarin dosingInitial warfarin dosing will be determined using the same algorithm as in the experimental group, but only including the clinical factors and not including the genotype information |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- Adults ≥18 years old
- Patients who are beginning warfarin for a variety of diseases or conditions that require long-term oral anticoagulation with target INR > 2.0 for at least 3 months
- Subjects that will be following up in UNC anticoagulation clinics at the Ambulatory Care Center or the Family Medicine Center
Key exclusion criteria (6 listed)
- Patients who are unable to complete the study materials (questionnaires) with or without assistance (for example, those with dementia)
- Non-English speaking patients
- Patients who are being started on anticoagulation intended to last < 3 months or whose target INR is < 2.0
- Patients who have a history of treatment with warfarin and a known dose requirement will be excluded (as they should be restarted on the previous dose)
- Pregnant women will be excluded because warfarin is a teratogen and pregnant women should not take the medication
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Genotype-guided dose determinationPatients in both arms will be treated with warfarin. Those in the experimental group will have initial doses determined using an algorithm (from www.warfarindosing.org) incorporating genetic and clinical factors. Those in the control group will have doses determined using the same algorithm, but without including the genetic factors. | Other | Genotype-guided warfarin dosing |
| Non-genotype guided warfarin dosingThose in the control group will have doses determined using the same algorithm, but without including the genetic factors. | Other | Non-genotype guided warfarin dosing |
Primary outcome
Time in therapeutic range (TTR)
Time frame: 3 months
Number of anticoagulation visits
Time frame: 3 months
9 secondary outcomes
Proportion of INRs > 4
Time frame: 3 months
Major bleeding events
Time frame: 3 months
Minor bleeding events
Time frame: 3 months
Thromboembolic complications
Time frame: 3 months
All-cause mortality
Time frame: 3 months
Time to therapeutic dose
Time frame: 3 months
Emergency department visits
Time frame: 3 months
Hospitalizations
Time frame: 3 months
Costs and cost-effectiveness
Time frame: 3 months
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 May 2016.
- Background: PubMed 11157645Levine MN, Raskob G, Landefeld S, Kearon C. Hemorrhagic complications of anticoagulant treatment. Chest. 2001 Jan;119(1 Suppl):108S-121S. doi: 10.1378/chest.119.1_suppl.108s.
- Background: PubMed 11867978Hafner JW Jr, Belknap SM, Squillante MD, Bucheit KA. Adverse drug events in emergency department patients. Ann Emerg Med. 2002 Mar;39(3):258-67. doi: 10.1067/mem.2002.121401.
- BackgroundMcWilliam A, Lutter R, Nardinelli C. Jointcenter; AEI-Brookings Joint Center For Regulatory Studies. Working Paper 06-23, November 2006
- Background: PubMed 15930419Rieder MJ, Reiner AP, Gage BF, Nickerson DA, Eby CS, McLeod HL, Blough DK, Thummel KE, Veenstra DL, Rettie AE. Effect of VKORC1 haplotypes on transcriptional regulation and warfarin dose. N Engl J Med. 2005 Jun 2;352(22):2285-93. doi: 10.1056/NEJMoa044503.
- Background: PubMed 16611750Li T, Lange LA, Li X, Susswein L, Bryant B, Malone R, Lange EM, Huang TY, Stafford DW, Evans JP. Polymorphisms in the VKORC1 gene are strongly associated with warfarin dosage requirements in patients receiving anticoagulation. J Med Genet. 2006 Sep;43(9):740-4. doi: 10.1136/jmg.2005.040410. Epub 2006 Apr 12.
- Background: PubMed 15947090Sconce EA, Khan TI, Wynne HA, Avery P, Monkhouse L, King BP, Wood P, Kesteven P, Daly AK, Kamali F. The impact of CYP2C9 and VKORC1 genetic polymorphism and patient characteristics upon warfarin dose requirements: proposal for a new dosing regimen. Blood. 2005 Oct 1;106(7):2329-33. doi: 10.1182/blood-2005-03-1108. Epub 2005 Jun 9.
- BackgroundMillican, E., et al. Blood, Epub ahead of print, Mar 26, 2007
- Background: PubMed 15841315Voora D, Eby C, Linder MW, Milligan PE, Bukaveckas BL, McLeod HL, Maloney W, Clohisy J, Burnett RS, Grosso L, Gatchel SK, Gage BF. Prospective dosing of warfarin based on cytochrome P-450 2C9 genotype. Thromb Haemost. 2005 Apr;93(4):700-5. doi: 10.1160/TH04-08-0542.
- Derived from this study: PubMed 24088130Jonas DE, Evans JP, McLeod HL, Brode S, Lange LA, Young ML, Shilliday BB, Bardsley MM, Swinton-Jenkins NJ, Weck KE. Impact of genotype-guided dosing on anticoagulation visits for adults starting warfarin: a randomized controlled trial. Pharmacogenomics. 2013 Oct;14(13):1593-603. doi: 10.2217/pgs.13.145.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Daniel E Jonas, MD, MPH principal investigator
UNC Institute for Pharmacogenomics and Individualized Therapy
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Genotype-guided dose determination and Non-genotype guided warfarin dosing in people with Atrial Fibrillation and Deep Vein Thrombosis, run by University of North Carolina, Chapel Hill at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 6 May 2016. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Time in therapeutic range (TTR) (time frame: 3 months). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT00904293, which also lists 9 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 May 2016.