Absher et al developed a score that can be used to predict if a patient is likely to require a daily warfarin dose greater than 5 mg per day. The authors are from Wesley Long Community Hospital and LeBauer HealthCare in Greensboro, North Carolina.
Parameters:
(1) age
(2) gender
(3) ethnicity
(4) vitamin K intake
(5) body weight
(6) exposure to a potentiator of warfarin effect
|
Parameter |
Adjusted Odds Ratio |
95% CI |
p value |
|
age < 55 years |
6.8 |
1.9 – 24.0 |
0.003 |
|
male gender |
4.7 |
1.8 – 12.4 |
0.002 |
|
African American |
4.4 |
1.3 – 14.6 |
0.017 |
|
vitamin K intake > 400 µg/d |
4.1 |
1.1 – 15.4 |
0.036 |
|
body weight >= 91 kilograms |
2.9 |
1.2 – 7.2 |
0.021 |
|
potentiator of warfarin effect |
0 |
|
|
where:
• Drugs potentiating warfarin effect include: amiodarone, clarithromycin, fluconazole, gemfibrozil, metronidazole, miconazole.
|
Parameter |
Finding |
Points |
|
age |
< 55 years |
4 |
|
|
>= 55 years |
0 |
|
gender |
male |
3 |
|
|
female |
0 |
|
ethnicity |
African American |
3 |
|
|
other |
0 |
|
vitamin K intake |
> 400 micrograms per day |
3 |
|
|
<= 400 micrograms per day |
0 |
|
body weight |
>= 91 kilograms |
2 |
|
|
< 91 kilograms |
0 |
|
concomitant use of a significant potentiator of warfarin effect |
yes |
0 |
|
|
no |
1 |
predictor score =
= (points for potentiator) * SUM(points for other 5 parameters)
Interpretation:
• minimum score: 0
• maximum score: 15
• The higher the score the more likely that the person will require a higher warfarin dose.
|
Predictor Score |
Likelihood of Requiring High Dose Warfarin Therapy |
|
<= 3 |
low |
|
4 – 7 |
intermediate |
|
>= 8 |
high |
Specialty: Hematology Oncology, Clinical Laboratory, Pharmacology, clinical
ICD-10: ,
