Factor V Leiden Prevalence in DVT
Factor V Leiden is present in approximately 15-20% of patients with an initial episode of deep vein thrombosis, making it the most common known heritable thrombophilic risk factor. 1
Prevalence Data
The prevalence of Factor V Leiden in DVT patients varies based on patient selection criteria:
Unselected DVT patients (all ages): Factor V Leiden is found in roughly 11-20% of individuals presenting with their first episode of venous thrombosis 1
Selected populations (younger or recurrent DVT): When patients are selected to be under 50 years old and/or have recurrent thrombosis, up to 40% carry the Factor V Leiden genotype 1
General population baseline: Approximately 5% of the Caucasian population carries Factor V Leiden in heterozygous form, with lower rates in Hispanic-Americans and African-Americans, and virtual absence in Africans and Asians 1
Clinical Context and Risk Magnitude
The mutation confers different levels of thrombotic risk depending on zygosity:
Heterozygotes: 4- to 7-fold increased risk for initial VTE episode, with a lifetime risk of approximately 10% 1
Homozygotes: 9- to 80-fold increased risk, with lifetime risk exceeding 80% 1
Important Clinical Caveat: The Factor V Leiden Paradox
Factor V Leiden shows preferential association with DVT rather than pulmonary embolism:
Only 6-9% of patients presenting with isolated symptomatic pulmonary embolism carry Factor V Leiden 2, 3
In contrast, 17% of patients presenting with isolated DVT carry the mutation 3
This "Factor V Leiden paradox" suggests the mutation may lead to thrombi with different structural characteristics that are less prone to embolization 3