Prospective Evaluation of an Extended Interval of INR Follow-up in a VA Anticoagulation Service

Study Overview
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Brief Summary
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The purpose of this study is to determine the feasibility, safety, and acceptability of implementing an extended interval of INR follow-up in Veterans on a stable dose of warfarin in the Anticoagulation Clinic at the William S. Middleton Memorial Veterans Hospital. All participants will be provided usual care from the anticoagulation clinic, except for the interval between INRs. If the participant continues to be on a stable dose of warfarin and the INRs are within the goal range of 2-3 (including lab variation), follow-up visits will be scheduled following an extended interval protocol. Patient satisfaction will be evaluated at various points throughout the study. Additionally provider satisfaction, confidence, and knowledge of the extended interval protocol will be analyzed. Bleeding and thromboembolic events will be evaluated to ensure the safety of an extended follow-up interval.

Detailed Description
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The purpose of this study is to determine the feasibility, safety, and acceptability of implementing an extended interval of INR follow-up in Veterans on a stable dose of warfarin in the Anticoagulation Clinic at the William S. Middleton Memorial Veterans Hospital. All participants will be provided usual care from the anticoagulation clinic, except for the interval between INRs. If the participant continues to be on a stable dose of warfarin and the INRs are within the goal range of 2-3 (including lab variation), follow-up visits will be scheduled following an extended interval protocol, from 5-6 weeks, to 7-8 weeks, to 11-12 weeks and then continued with 11-12 week visits if INRs continue to remain in goal range and appropriate for the patient. Patient satisfaction will be evaluated at baseline, 6-, 12-, and 24-months. Additionally provider satisfaction, confidence, and knowledge of the extended interval protocol will be analyzed. Bleeding and thromboembolic events will be evaluated to ensure the safety of an extended follow-up interval.

Official Title
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Prospective Evaluation of an Extended Interval of INR Follow-up in a VA Anticoagulation Service

Conditions
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Anticoagulation

Intervention / Treatment
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* Drug: Warfarin


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 18 years of age or older requirement for indefinite warfarin therapy target INR of 2-3 stable weekly warfarin dose for the past 6 months (not more than a single, one-time adjustment (boost/omission) in the past 6 months, planned interruption for a procedure or surgery with INR(s) out of range in the past 6 months would not exclude a patient) a patient of the Madison VA anticoagulation clinic for the previous 12 months Exclusion Criteria: consistently drink ≥4 alcoholic beverages/day or a documented episode of alcohol binging in the past 6 months diagnosis of cancer and on active chemotherapy/radiotherapy in the past 3 months life expectancy of < 1 year enrolled in other investigational drug protocols only receiving anticoagulation care at the Madison VA for part of the year (e.g. snowbirds) receiving visiting nurse services for INR monitoring thrombocytopenia (<100K) within past 12 months history of bleeding or thromboembolism requiring medical intervention within past 6 months treatment for active liver disease (e.g. hepatitis) diagnosis or documentation in EMR suggesting cognitive impairment activated power of attorney inability to provide informed consent non-English speaking unstable mental health disorder that impairs judgment history of non-adherence to anticoagulation clinic policies and procedures (i.e. missed appointments, self-adjustment of warfarin dose, nonadherence, etc.).

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Intervention Arm<br>All patients in the study will be in the intervention arm. | Drug: Warfarin<br>* If the patient's INRs stay within goal range, their interval of INR follow-up will be extended based on a protocol to a maximum of 12 weeks.<br>* Other names: Coumadin;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Rates of Participant Accrual | Number of participants who enroll vs. number of individuals invited | up to 2.25 years | 
| Number of Participants Able to be Scheduled for at Least One 12-week Interval | This outcome will determine the number of participants able to be scheduled for at least one 12-week interval | 24 months | 
| Number of Participants Scheduled for at Least 4 Consecutive 12-week Intervals | The outcome will determine the number of participants scheduled for at least 4 consecutive 12-week intervals | 24 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Frequency of Appointments From Baseline to End of Study | This outcome will evaluate the change in frequency of appointments from baseline to end of study (at 12 and 24 months) | 12 and 24 months | 
| Bleeding and Thromboembolic Events From Baseline | This outcome will determine the number of bleeding and thromboembolic events from baseline | 24 months | 
| Change in Time in Therapeutic Range From Baseline | The outcome will evaluate the change in time in therapeutic range (TTR) from baseline (intention-to-treat) | 6, 12, and 24 months | 
| Patient Satisfaction Through Total DASS Score | Patient satisfaction through total DASS score. DASS = Duke Anticoagulation Satisfaction Scale. 25-item scale.Higher numbers indicate worsening satisfaction ranging from 25-175. Seven-point ordinal scale (not at all = 1, very much = 7). | baseline, 6 months, 12 months, 24 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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International Normalized Ratio, Warfarin