Table 1.
Prevalence of inherited thrombophilia and relative risk estimates for various clinical manifestations
| Antithrombin deficiency | Protein C deficiency | Protein S deficiency | Factor V Leiden | Prothrombin 20210A mutation | |
|---|---|---|---|---|---|
| Prevalence in the general population* | 0.02% | 0.2% | 0.03%-0.13% | 3%-7% | 0.7%-4% |
| Prevalence in consecutive patients with VTE* | 1% | 3% | 2% | 20% | 5% |
| Relative risk for a first VTE† | 5-10 | 4-6.5 | 1-10 | 3-5 | 2-3 |
| Relative risk for recurrent VTE | 1.9-2.6 | 1.4-1.8 | 1.0-1.4 | 1.4 | 1.4 |
| Relative risk for arterial thrombosis | No association | No consistent association | No consistent association | 1.3 | 0.9 |
| Relative risk for pregnancy complications | 1.3-3.6 | 1.3-3.6 | 1.3-3.6 | 1.0-2.6 | 0.9-1.3 |
Figures are derived from studies that are reviewed in detail elsewhere.60
*
Population prevalences vary with geographic regions.
†
Relative risks were derived, where possible, from family studies comparing the risk for a first VTE in thrombophilic relatives vs in nonthrombophilic relatives. Hence, the relative risk is not consistent with the ratio between the prevalence in consecutive VTE patients and in the general population.