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, risk factors are grouped into patient-related factors (personal factors, disease states, and clotting disorders) and admission-related factors (including surgical and procedural factors).
- 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.