Table 2.
Prevalence of thrombophilic risk factors and associated OR of venous thromboembolism
| Coagulation defect | Women with history of thromboembolism during pregnancy and puerperium (n = 243) | Control women (n = 243) | Univariate analysis | ||||
|---|---|---|---|---|---|---|---|
| P value | OR | 95% CI | |||||
| % | No. with defect/total no. | % | No. with defect/total no. | ||||
| Genetic defects*,† | |||||||
| FVL heterozygous | 28.44 | 60/211 | 8.02 | 19/237 | <.0001 | 4.6 | 2.65-7.95 |
| FVL homozygous | 2.58 | 4/155 | 0.15‡ | <.0001 | 17.2 | 6.3-47 | |
| Prothrombin G20210A heterozygous | 7.93 | 13/164 | 2.68 | 6/224 | .029 | 3.1 | 1.16-8.41 |
| FVL and prothrombin G20210A (compound heterozygous) | 7.93 | 13/164 | 0.18‡ | <.0001 | 47 | 26-84 | |
| Antithrombin deficiency (activity) | |||||||
| Mild deficiency (cutoff <90%) | 9.18 | 19/207 | 4.83 | 10/207 | .083 | 2.0 | 0.9-4.93 |
| Severe deficiency (cutoff <60%) | 0.97 | 2/207 | 0.02‡ | <.0001 | 49 | 11.5-204 | |
| Protein C deficiency (activity) | |||||||
| Mild deficiency (cutoff <76%) | 10.67 | 19/178 | 4.98 | 10/201 | .037 | 2.3 | 1.03-5.1 |
| Severe deficiency (cutoff <50%) | 1.69 | 3/178 | 0.31‡ | .019 | 5.5 | 1.8-17.3 | |
| Protein S deficiency (activity) | |||||||
| Mild deficiency (cutoff <56%) | 10.73 | 19/177 | 4.50 | 9/200 | .021 | 2.6 | 1.12-5.8 |
| Severe deficiency (cutoff <40%) | 3.95 | 7/177 | 1.0 | 2/200 | .089 | 4.1 | 0.84-19.9 |
| Free protein S deficiency (concentration) | |||||||
| Mild deficiency (cutoff <57%) | 12.1 | 19/157 | 4.17 | 6/144 | .02 | 3.2 | 1.23-8.17 |
| Severe deficiency (cutoff <40%) | 6.37 | 10/157 | 0.69 | 1/144 | .011 | 9.7 | 1.2-76.9 |
| Family history of VTE in first-degree relatives§ | 39.1 | 95/243 | 16.5 | 40/243 | <.0001 | 3.3 | 2.2-5.0 |
There were no patients and no control women with a positive result for lupus anticoagulant or cardiolipin antibodies.
These categories are exclusive, ie, to be included in one of the groups, subjects must display the exact genetic constellation. This leads to, for example, individuals with compound heterozygous FVL and prothrombin G20210A to be excluded from both the heterozygous FVL and the heterozygous prothrombin G20210A groups and vice versa.
After adjustment for a positive family history, the OR was 4.3 (95% CI, 3.15-5.76) for heterozygous FVL, 23 (95% CI, 8.3-63.5) for homozygous FVL, 4.5 (95% CI, 2.4-7.8) for heterozygous prothrombin G20210A, and 61 (95% CI, 33.8-113) for compound heterozygous FVL and prothrombin G20210A.
Because no normal woman had a homozygous defect or a compound defect, the estimated ORs were calculated on the basis of the probability of a homozygous defect in this group using the Hardy-Weinberg equilibrium. Because no normal woman had an antithrombin activity <60% or a protein C activity <50%, the ORs for deficiencies of antithrombin activity <60% and of protein C activity <50% were calculated on the basis of the prevalence of antithrombin deficiency type I of 0.02% in the general population38 and on the basis of the prevalence of protein C deficiency of 0.3% in the general population,39 respectively.
The OR for a positive family history of VTE was 2.8 (95% CI, 2.1-3.7) after adjustment for heterozygous FVL, 3.5 (95% CI, 2.5-4.8) after adjustment for homozygous FVL, 3.71 (95% CI, 2.7-5.1) after adjustment for heterozygous prothrombin G20210A, and 3.7 (95% CI, 2.7-5.1) after adjustment for compound heterozygous FVL and prothrombin G20210A.