Final experimental design
| Factor | Level 1 | Level 2 | Level 3 | Level 4 | Level 5 | Level 6 |
| Sex | female | male | ||||
| Age | <65 | >65 | ||||
| BMI | underweight | normal weight | overweight | |||
| Idiopathic | no | yes | ||||
| Type of VTE | distal DVT | distal DVT with signs of PTS | proximal DVT | proximal DVT with signs of PTS | non-massive PE | massive PE |
| Previous VTE | no | yes (2 years ago) | ||||
| Family history of VTE | no | yes | ||||
| History of major bleeding | no | yes | ||||
| Thrombophilia | none | acquired | inherited | |||
| Renal function | normal | insufficient (<50 mL/min) | ||||
| Alcohol or substance abuse | no | yes | ||||
| Absolute indication for aspirin | no | yes |
BMI, body mass index; DVT, deep vein thrombosis; PE, pulmonary embolism; VTE, venous thromboembolism.