Risk factors for venous thromboembolism in patients with human immunodeficiency virus infection.

Prevention and treatment of venous thromboembolism are gaining attention in the lay and medical communities because of an increase in frequency, cost, and risk factors. Evidence shows that patients with human immunodeficiency virus (HIV) have multiple risk factors and a 2-10-fold increased risk for venous thromboembolism compared with the general population. A higher rate of venous thromboembolism also occurs in patients with HIV who are younger than 50 years (3.31% vs 0.53% in age-matched healthy controls, p<0.0001), have a CD4(+) cell count less than 200 cells/mm³, or have a diagnosis of acquired immunodeficiency syndrome. Both protein S and C deficiencies--disorders that may predispose individuals to thrombotic disease--are considered risk factors; in addition, the use of protease inhibitors and the presence of active opportunistic infections or antiphospholipid antibodies may be associated with venous thromboembolism. It is imperative that all risk factors for venous thromboembolism be identified and incorporated into medical decision making for high-risk patients, including those with HIV. The classification and mechanism of these risk factors are not well understood. Long-term, prospective studies assessing the factors associated with venous thromboembolism in patients with HIV are needed. Risk stratification systems or screening tools, as well as effective preventive measures, must be developed.