Thrombophilia testing in people with venous thromboembolism: systematic review and cost-effectiveness analysis.

OBJECTIVES To assess whether thrombophilia testing following a venous thrombotic event is clinically effective and cost-effective in the management of thrombosis compared with no testing for thrombophilia. DATA SOURCES Major electronic databases were searched from September to November 2006. REVIEW METHODS A systematic review of the clinical effectiveness and cost-effectiveness literature was undertaken according to standard methods. A discrete event simulation model was constructed to assess the cost-effectiveness of changing the standard 3-month duration of warfarin treatment to 10 years, 20 years or lifelong. RESULTS No clinical studies were identified that met the inclusion criteria for the systematic review. Further literature searches and clinical opinion were therefore used to inform the cost-effectiveness analysis. Thrombophilia testing in patients with pulmonary embolism (PE) had an estimated mean cost per quality-adjusted life-year (QALY) of below 20,000 pounds regardless of sex or age. In patients with a previous deep vein thrombosis (DVT), thrombophilia testing had an estimated mean cost per QALY of below 20,000 pounds in men aged 69 years or less and in women aged 49 years or less. The estimated duration of warfarin treatment (lifelong, 20 years, 10 years or no extended treatment) that was most cost-effective is presented for each age, sex, initial venous thromboembolism (VTE) event and type of thrombophilia. CONCLUSIONS In terms of determining the duration of anticoagulation management, scenarios were found in which the cost per QALY of thrombophilia testing was below 20,000 pounds. However, these results are subject to great uncertainty, largely because of lack of knowledge about the increased risk of recurrence with each type of thrombophilia. Results are influenced by the fact that men have a greater risk of recurrence than women and by the fact that the frequency of adverse events associated with warfarin treatment increases with age. Further research, for example on the likely sensitivity and specificity of the tests for specific types of thrombophilia, is needed to reduce the uncertainty associated with these results. Studies comparing patients with VTE tested for thrombophilia with those whose risk assessment was based on personal and family history of thrombosis would also be beneficial.