Kahn et al developed a clinical prediction index for deep vein thrombosis (DVT) in patients with leg symptoms. Since clinical signs and symptoms may be inaccurate in the diagnosis of DVT, such an index may help reduce the use of unnecessary diagnostic tests in patients at low risk for thrombosis. The authors are from Jewish General and Montreal General Hospital in Montreal, Canada.

Risk Factor Identified by Multivariate Analysis

Odds Ratio

95% Confidence Interval

male sex


1.4 – 5.7

orthopedic surgery


2.2 – 13.6



1.2 – 3.9

superficial venous dilation on exam


1.4 – 5.7


clinical index =

= SUM(number of risk factors present)



• minimum index: 0

• maximum index: 4

• A patient with a moderate to high risk for DVT might benefit from contrast venography or other diagnostic study.


Clinical Index

Risk of Deep Vein Thrombosis in Leg


low risk

1 – 2

moderate risk

3 - 4

high risk


To read more or access our algorithms and calculators, please log in or register.