Table 2.
Estimated incidence of a first episode of VTE in carriers of various thrombophilias (data apply to individuals with at least 1 symptomatic first-degree relative)
| Antithrombin, protein C, or protein S deficiency | Factor V Leiden, heterozygous | Prothrombin 20210A mutation | Factor V Leiden, homozygous | |
|---|---|---|---|---|
| Overall, %/y (95% CI) | 1.5 (0.7-2.8) | 0.5 (0.1-1.3) | 0.4 (0.1-1.1) | 1.8 (0.1-4.0)* |
| Surgery, trauma, or immobilization, %/episode (95% CI)† | 8.1 (4.5-13.2) | 1.8 (0.7-4.0) | 1.6 (0.5-3.8) | — |
| Pregnancy, %/pregnancy (95% CI) | 4.1 (1.7-8.3) | 2.1 (0.7-4.9) | 2.3 (0.8-5.3) | 16.3‡ |
| During pregnancy, % (95% CI) | 1.2 (0.3-4.2) | 0.4 (0.1-2.4) | 0.5 (0.1-2.6) | 7.0‡ |
| Postpartum period, % (95% CI) | 3.0 (1.3-6.7) | 1.7 (0.7-4.3) | 1.9 (0.7-4.7) | 9.3‡ |
| Oral contraceptive use, %/y of use (95% CI) | 4.3 (1.4-9.7) | 0.5 (0.1-1.4) | 0.2 (0.0-0.9) | — |
Figures are derived from numerous family studies, reviewed in detail elsewhere.60
*
Based on pooled OR of 18 (95% CI, 8-40) and an incidence of 0.1% in noncarriers.
†
These risk estimates of symptomatic VTE for a large part reflect the situation before thrombosis prophylaxis was routine patient care.
‡
Data from family studies, risk estimates lower in other settings.