Quantification of risk factors for venous thromboembolism: a preliminary study for the development of a risk assessment tool.

BACKGROUND AND OBJECTIVES Venous thromboembolism is a frequent and serious disorder influenced by numerous factors. As the first step in creating a tool to assess an individual patient's risk of venous thromboembolism, we carried out a literature review in order to quantify risk factors for venous thromboembolism. EVIDENCE AND INFORMATION SOURCES Risk factors were identified as being either predisposing, that is, those risks presented by a patient prior to hospital admission, or exposing, that is, those risks occurring when a patient is hospitalized for a certain medical condition or surgical procedure. Predisposing risk factors were classified with regard to the patients' characteristics (including general characteristics and inherent risk factors), and recent and chronic clinical conditions. RESULTS The major predisposing factors among the patients' characteristics were age, hormonal therapy and personal history of venous thromboembolism, along with inherited coagulation factor abnormalities. Clinical situations associated with the highest risk of venous thromboembolism were recent surgery, hospitalization for medical conditions and immobilization, moderate to severe congestive heart failure, and malignancy. CONCLUSIONS This literature review will assist in the development of a suitable risk assessment tool for aiding healthcare professionals to decide whether to employ thromboprophylaxis, and, if so, to select the appropriate type and duration of prophylaxis.