Certain factors and conditions predispose to VTE. The risk of developing VTE depends on the condition and/or procedure for which the patient is admitted and on any predisposing risk factors (such as age, obesity, and concomitant conditions) .
Both medical and surgical patients can be at increased risk of VTE, depending on mobility, duration of surgery, trauma, and the presence of particular risk factors .
For the purposes of assessing a patient for VTE risk on admission to hospital, two groups of factors are relevant ;
- Personal risk factors include older age, previous or family history of VTE, obesity, varicose veins, the use of oestrogens (oral contraceptives or hormone replacement therapy), and immobility.
- Diseases that increase the risk of VTE, including malignancy, medical illnesses including congestive heart failure, acute infectious and inflammatory conditions, and spinal cord injury with paralysis, and stroke.
- Thrombophilia, both genetic (e.g. Factor V Leiden and Prothrombin 20210 mutations) and acquired (e.g. antiphospholipid syndrome, myeloproliferative disorders and acquired activated protein C resistance).
- These include acute surgical admission, major surgery (i.e. longer than 60 minutes), and surgery resulting in prolonged immobility; critical care admission; and admission for major orthopaedic surgery (hip and knee replacement) or for hip fracture .