Discriminant Formula of Clayton et al for Prediction of Post-Operative Deep Vein Thrombosis

 

Parameters:

(1) euglobin clot lysis time in minutes (a measure of plasminogen activator. The fibrinolytic activity is inversely related to the clot lysis time.)

(2) concentration of fibrin-related antigen in mg/L (related to fibrin split products)

(3) age in years

(4) percentage overweight for height

(5) presence of varicose veins (1 point if present, 0 points if absent)

 

percentage overweight for height =

= ((weight in kilograms) – (ideal weight for height)) / (ideal weight for height) * 100%

 

where:

• The ideal body weight can be calculated based on the equations in Chapter 2.

 

discriminant score =

= (0.009 * (euglobin clot lysis time)) + (0.22 * (fibrin related antigen)) + (0.085 * (age in years)) + (0.043 * (percentage overweight)) + (2.19 * (points for varicose veins)) – 11.3

 

Interpretation:

Score	Risk of Thrombosis
> 1	high
-1 to +1	moderate
> -3 to < -1	low
<= -3	very low

from diagram page 911, Clayton (1976)