Patient selection: suspected deep vein thrombosis (DVT)
Parameters:
(1) immobilization (I), with recent bedridden status > 3 days or major surgery within past 4 weeks)
(2) difference in circumference (D), with calf circumference of affected leg >= 3 cm greater than for the calf of the unaffected leg
(3) venous thromboembolism in past (V)
(4) tumor (T), with active cancer (ongoing treatment, previous 6 months, palliation)
Additional parameters for adjusted I-DVT score:
(5) use of oral contraceptives
(6) DVT more likely than an alternative diagnosis
|
Parameter
|
Finding
|
I-DVT
|
Adjusted I-DVT
|
|
immobilization
|
no
|
0
|
0
|
|
|
yes
|
1
|
1
|
|
difference in calf circumference
|
< 3 cm
|
0
|
0
|
|
|
>= 3 cm
|
1
|
1
|
|
history of VTE
|
no
|
0
|
0
|
|
|
yes
|
1
|
1
|
|
active tumor
|
no
|
0
|
0
|
|
|
yes
|
1
|
1
|
|
oral contraceptive
|
no or male
|
NA
|
0
|
|
|
yes and female
|
NA
|
1
|
|
DVT more likely
|
no
|
NA
|
0
|
|
|
yes
|
NA
|
1
|
total I-DVT score =
= SUM(points for all 4 parameters)
total adjusted I-DVT score =
= SUM(points for all 6 parameters)
Interpretation:
• minimum score: 0
• maximum I-DVT score: 4
• maximum adjusted I-DVT score: 6
• DVT was considered likely if the I-DVT was >=1 or the adjusted I-DVT was >=3.
Performance:
• The area under the ROC curve was 0.65 vs 0.70 for the Wells score.
• The assumption is that the deep vein thrombosis is unilateral.
