Risk of first venous thrombosis in 2479 relatives of 877 probands associated with thrombophilic defects
| Index defect* . | Observation years . | Relatives with event . | Annual incidence, % (95% CI) . | Adjusted relative risk† (95% CI) . |
|---|---|---|---|---|
| Antithrombin deficiency, n = 60 | 1416 | 25 | 1.77 (1.14-2.60) | 28.2 (13.5-58.6) |
| Protein C deficiency, n = 91 | 2301 | 35 | 1.52 (1.06-2.11) | 24.1 (13.7-42.4) |
| Protein S deficiency, n = 94 | 1846 | 35 | 1.90 (1.32-2.64) | 30.6 (26.9-55.3) |
| High FVIII, n = 776 | 26 315 | 130 | 0.49 (0.41-0.51) | 7.1 (4.3-11.8) |
| Factor V Leiden, n = 652 | 18 237 | 89 | 0.49 (0.39-0.60) | 7.5 (4.4-12.6) |
| Prothrombin 20210G>A, n = 288 | 8324 | 28 | 0.34 (0.22-0.49) | 5.2 (2.8-9.7) |
| Index defect* . | Observation years . | Relatives with event . | Annual incidence, % (95% CI) . | Adjusted relative risk† (95% CI) . |
|---|---|---|---|---|
| Antithrombin deficiency, n = 60 | 1416 | 25 | 1.77 (1.14-2.60) | 28.2 (13.5-58.6) |
| Protein C deficiency, n = 91 | 2301 | 35 | 1.52 (1.06-2.11) | 24.1 (13.7-42.4) |
| Protein S deficiency, n = 94 | 1846 | 35 | 1.90 (1.32-2.64) | 30.6 (26.9-55.3) |
| High FVIII, n = 776 | 26 315 | 130 | 0.49 (0.41-0.51) | 7.1 (4.3-11.8) |
| Factor V Leiden, n = 652 | 18 237 | 89 | 0.49 (0.39-0.60) | 7.5 (4.4-12.6) |
| Prothrombin 20210G>A, n = 288 | 8324 | 28 | 0.34 (0.22-0.49) | 5.2 (2.8-9.7) |
All P values were less than .001.
As concomitance of defects occurred frequently, relatives could be counted twice or more.
Adjusted for age, sex, and clustering in families and compared with relatives with no thrombophilic defects (n=951; 27 028 observation years; 12 events; annual incidence 0.05%; 95% CI, 0.02-0.08).