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Model of Zhu et al for Determining a Patient's Daily Dose Requirement for Warfarin

Purpose: To determine a patient's total oral daily dose of warfarin using the model of Zhu et al.

Description

Zhu et al developed a model for predicting the total daily dose of  warfarin based on the patient's physical and genotypic features. This can control for a number of factors affecting the variability in dose. The authors are from the University of Louisville, Luminex Molecular Diagnostics and PGXL Laboratories.


VKORC1 = vitamin K epoxide reductase complex, subunit 1

CYP = cytochrome P450

 

Parameters:

(1) age in years

(2) gender

(3) body weight in pounds

(4) VKORC1 (-1639AA) genotype

(4) VKORC1 (-1639BB) genotype

(6) CYP2C9*2 genotype

(7) CYP2C9*3 genotype

 

Parameter

Finding

Points

gender

female

0

 

male

1

VKORC1 (-1639AA)

AA

1

 

GA

0

 

GG

0

VKORC1 (-1639GG)

AA

0

 

GA

0

 

GG

1

CYP2C9*2

0 alleles

0

 

1 allele

1

 

2 alleles

2

CYP2C9*3

0 alleles

0

 

1 allele

1

 

2 alleles

2

 

where:

• The alleles of CYP2C9 associated with decreased metabolic activity and increased risk of bleeding during warfarin therapy: CYP2C9*2, CYP2C9*3, CYP2C9*4, CYP2C9*5, CYP2C9*6.

 

X =

= (-0.008 * (age in years)) + (0.116 * (points for gender)) + (0.004 * (weight in lbs)) - (0.376 * (points for VKORC1 1639AA)) + (0.271 * (points for VKORC1 1639GG)) - (0.307 * (points for CYP2C9*2)) - (0.318 * (points for CYP2C9*3)) + 1.35

 

daily dose in mg =

= EXP(X)


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Specialty

Objective

ICD-10