| 1 | Age 41 – 60 years | 36 | 34.6 |
| Minor surgery planned | 46 | 21.2 |
| History of prior major surgery | 2 | 1.0 |
| BMI > 25 kg/m2 | 32 | 14.8 |
| Swollen legs (current) | 1 | 0.5 |
| Varicose veins | 6 | 2.8 |
| Sepsis (< 1 month) | 3 | 1.4 |
| Abnormal pulmonary function (COPD) | 1 | 0.5 |
| Congestive heart failure (< 1 month) | 1 | 0.5 |
| History of inflammatory bowel disease | 5 | 2.3 |
| 2 | Aged 61 – 74 years | 55 | 25.3 |
| Laparoscopic surgery (> 45 min) | 10 | 4.6 |
| Major open surgery (> 45 min) | 161 | 74.2 |
| Prior or present malignant diseases | 4 | 1.8 |
| Confined to bed (> 72 hours) | 53 | 24.4 |
| Immobilizing plaster cast (< 1 month) | 36 | 16.6 |
| Central venous catheter access | 1 | 0.5 |
| 3 | Aged ≥ 75 years | 36 | 12.0 |
| History of VTE | 1 | 0.5 |
| 5 | Elective major lower extremity arthroplasty | 39 | 18.0 |
| Hip, pelvic fracture (< 1 month) | 41 | 18.9 |
| Multiple traumas | 7 | 3.2 |