Epidemiologia

Clinical Practice Guideline for Anticoagulation Management
This guideline is to inform practitioners of the Standard of Care for providing safe and effective anticoagulation management for ambulatory patients. 1. INITIATION OF WARFARIN A. Prior to initiating Warfarin therapy providers need to provide patient education including: 1. Indication and action of Warfarin 2. INR (InternationalNormalized Ratio) monitoring, dose adjustments and duration of therapy 3. Possible side effects of Warfarin, including signs and symptoms of bleeding 4. Drug interactions 5. Dietary implications on Warfarin 6. Special considerations on Warfarin: illness, interruption in therapy, or as indicated 7. Importance of compliance with lab work, telephone calls, and appointments B. Bleeding risk must be assessedprior to initiation of Warfarin therapy. C. Baseline Hgb is assessed and followed annually. A low Hgb will be repeated in 6 months. D. Initiation of Warfarin at a dose of 4-5 mg daily is recommended, with smaller doses indicated for the elderly or debilitated patient. Loading doses are not recommended. E. Check initial INRs 3-4 days and 6-7 days after start of therapy. 1. Warfarin peak effect maynot be seen for 3-4 days. 2. INR may not stabilize for 10-14 days. F. The dosing of Warfarin must be individualized according to the patient’s response to the drug as reflected by the INR. G. Warfarin may be begun concurrently with Low Molecular Weight Heparin (LMWH) or Unfractionated Heparin (UFH) and should be overlapped for 4 to 5 days. 1. When the desired INR has been maintained for 1-2 days(depending on how strong the indication for anticoagulation is), the LMWH or UFH may be discontinued. 2. WARFARIN DOSAGE AND ADMINISTRATION A. Warfarin dosing must be individualized according to patient INR results. B. Individualized target INR ranges are determined according to the patient’s indication for anticoagulation and bleeding risk. C. Recommended INR range according to indication: seeTABLE A. D. Frequency of INR testing is variable over time, dictated by dose response and current clinical information. 1. Check INR 1-2 times per week at start of therapy x 2-3 weeks, until a therapeutic range is achieved and maintained for 2 consecutive tests. 2. For a new patient, INR checks be done weekly for 2-3 weeks once they have become therapeutic, as fluctuations are common. 3. INR testsevery 2 weeks are usually required for the next 2-3 weeks, then monthly 4. INR tests at no greater than 1 month intervals are recommended for patients who have achieved a stable therapeutic INR.
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5. Caution is recommended against frequently adjusting Warfarin doses for slightly out-ofrange results, i.e. within .2of range; instead repeat the INR in a week. E. Dose Adjustments 1. Response to Warfarin fluctuates over time, influenced by: a. Changes in other medications - ie; start of antibiotics - INR may need to be checked more often b. Intercurrent illness c. Dietary habits and changes in nutritional status d. Lifestyle habits including alcohol use, exercise, and travel e. Issues related to patientcompliance 2. Dose adjustments are best achieved by calculating the total weekly dose of Warfarin in milligrams per week and changing by only 5-15% according to established nomograms: see TABLES B and C. a. Slight variations in the amount of daily doses are forgiven by the relatively long half-life of Warfarin. b. Using single-strength Warfarin tablets minimizes the opportunity for dosing errors. c. Ingeneral, when a dose has been changed, allow 2 weeks before scheduling the next INR. d. Instructions to patients must be clear, concise and simple. 3. INRs that are supratherapeutic will be managed consistently and safely: see TABLE D.

TABLE A OPTIMAL THERAPEUTIC RANGE AND DURATION OF ANTICOAGULATION Target Indication INR Duration Comment Range Atrial Fibrillation/Flutter Age75 OR any risk...