Table 1. Baseline characteristics.
| MEGA follow-up study | Patient characteristics |
| N, (%) | 3,750 (100%) |
| Age, mean (SD) | 48 (13) |
| Sex, male (%) | 1,684 (45%) |
| BMI, mean (SD) | 27 (4.8) |
| Type of first event | |
| DVT | 2,231 (59%) |
| PE | 1,184 (32%) |
| PE + DVT | 335 (9%) |
| Provoked first event* | 2,592 (69%) |
| Trauma, surgery, immobilization† | 1,458 (39%) |
| Prolonged travel | 681 (18%) |
| Pregnancy, puerperium | 160 (4%) |
| Hormone use | 1,181 (31%) |
| Plaster cast | 198 (5%) |
| Unprovoked first event* | 1,082 (29%) |
| Tromsø study | Patient characteristics |
| N, (%) | 578 (100%) |
| Age, mean (SD) | 66.3 (14) |
| Sex, male (%) | 279 (48%) |
| BMI, mean (SD) | 27.0 (4.4) |
| Type of first event | |
| DVT | 348 (60.2%) |
| PE | 194 (33.6%) |
| PE + DVT | 36 (6.2%) |
| Provoked first event | 232 (40%) |
| Trauma, surgery, immobilization† | 190 (33%) |
| Pregnancy, puerperium | 6 (1%) |
| Hormone use | 36 (6%) |
| Unprovoked first event | 346 (60%) |
*Some data were missing for some variables (see S1 Table). Because concomitance of provoked risk factors occurred frequently, patients could be counted twice or more.
†Consists of surgery, leg injury, or confinement to bed for more than 3 days at home or in the hospital within 3 months before venous thrombosis.
Abbreviations: DVT, deep vein thrombosis; MEGA, Multiple Environment and Genetic Assessment of Risk Factors for Venous Thrombosis; PE, pulmonary embolism