Warfarin Inpt Nomogram and Dose Estimation

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Warfarin Inpatient Nomogram including dose prediction equation

>Beta< Version 1.0 - Date: July 2013

Patient Parameters

Age: Specify race:
Height: Weight:

Other (used to predict maintenance dose):

Target INR: Patient receiving amiodarone:
Smoker: DVT /PE present?:

Starting Dose:

Usual starting dose for most patients: 5 mg (Usual range: 4 -10 mg)

Select starting dose: mg (Return to this form if you need to alter the dose)

9th ACCP suggestion: Patients healthy enough to be treated as outpatients: Give warfarin 10 mg daily x 2 days. Further dosing should be based on INR monitoring. (Preferred to starting with an estimated maintenance dose.) (Grade 2C)

9th ACCP suggestion: Patients with acute VTE should be started on warfarin on day 1 or 2 of LMWH or heparin therapy e.g. do not wait several days to start treatment. (Grade 2C)

9th ACCP suggestions:

-For pt's started on UFH: Use weight-adjusted initial bolus of 80 units/kg followed by 18 units/kg per hour for VTE; or bolus of 70 units/kg followed by 15 units/kg per hour for cardiac or stroke patients) or use of a fixed dose (bolus 5,000 units followed by 1,000 units/hour) rather than alternative regimens (Grade 2C) .

-For outpatients with VTE treated with subcutaneous UFH: use weight-adjusted dosing (first dose 333 units/kg, then 250 units/kg) without monitoring rather than fixed or weight-adjusted dosing with monitoring (Grade 2C) .

-For patients receiving therapeutic LMWH who have severe renal-insufficiency (calculated CRCL <30 mL/min): Dose reduction is preferred rather than using standard doses (Grade 2C) .

-Pt's with VTE and body weight > 100 kg: fondaparinux treatment dose should be increased from the usual 7.5 mg to 10 mg daily SC (Grade 2C) .

Source: Holbrook A, Schulman S, Witt DM, Vandvik PO, Fish J, Kovacs MJ, Svensson PJ, Veenstra DL, Crowther M, Guyatt GH; American College of Chest Physicians. Evidence-based management of anticoagulant therapy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest. 2012 Feb;141(2 Suppl):e152S-84S. doi: 10.1378/chest.11-2295.

Equations Used:

BSA

1] (Weight) kg^0.425 x (Height) cm^0.725 x 0.007184 = BSA in M²

Reference: DuBois D, DuBois DF. A formula to estimate the approximate surface area if height and weight be known. Arch Int Med 1916;17:863-71.

Warfarin Dose Prediction

2]   exp [0.613 + (0.425 x BSA) - (0.0075 x age) + (0.156 x African-American race)
            + (0.216 x target INR) - (0.257 x amiodarone) + (0.108 x smokes)
                + 0.0784 x DVT/PE ]

Reference: Gage BF, Eby C, Johnson JA, Deych E, Rieder MJ, et al. Use of pharmacogenetic and clinical factors to predict the therapeutic dose of warfarin. Clin Pharmacol Ther. 2008 Sep;84(3):326-31. Epub 2008 Feb 27.

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Warfarin Inpt Nomogram and Dose Estimation