Table 4. Possibility of recurrence in risk groups.

Risk factor	Risk of recurrence
Temporary risk factor Non-surgical temporary risk factor Idiopathic or demonstrated thrombophilia Cancer	3-5% a year 15%-5 years 30%-5 years 15% for each year	Surgery, major internal disease Long travel, estrogen therapy, pregnancy, leg trauma + AT, PC, PS deficiency, homozygous
Isolated distal DVT	1/2 reduction in all ratios above
Idiopathic DVT	1/2 increase in all the above rates
AT: Atherothrombin; PC: Protein C; PS: Protein S; DVT: Deep vein thrombosis.