Table 4: Relative Risks of a First VTE in Selected Hypercoagulable States

Table 4:
Relative Risks of a First VTE in Selected Hypercoagulable States
Hypercoagulable State	Relative Risk of Lifetime Single VTE
Factor V Leiden	2-10
Prothrombin G20210A	2-6
Factor V Leiden and prothrombin G20210A ("double-heterozygous")	20.0
Protein C deficiency	6.5-31*
Protein S deficiency	2-36*
Antithrombin deficiency	5-40*
Hyperhomocysteinemia	2-4
Lupus anticoagulant	11
Anticardiolipin antibodies	3.2
* Relative risks are highly variable, depending on whether they were derived from population- or family-based studies. Differences in risk can be explained in part by greater difficulty in obtaining reliable population-based estimates due to the overall low prevalence of these disorders. It is also possible that event rates were overestimated in early familial studies.