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Outcomes/Effectiveness Research

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Patient self-testing of blood coagulation times has the potential to improve outcomes for patients at risk of stroke

Anticoagulation therapy that prevents blood clots is frequently prescribed for patients at risk of a first or subsequent stroke. Patients receiving this therapy must have regular blood tests to ensure that their blood is sufficiently thin to prevent clotting but not so thin as to produce excessive bleeding or hemorrhage.

With some patients, the optimal interval for testing may be once or twice a week, an office visit frequency that may be inconvenient for the patient and time consuming for the physician. The development of point-of-care blood analyzers now gives these patients the alternative of patient self-management (PSM) in which they perform most of their blood tests at home and make many of their own medication adjustments. PSM is a promising model of care that could improve anticoagulation management in a way similar to the improvement that glucose monitoring has brought to the management of diabetes. However, only a few studies have directly compared PSM to other approaches to anticoagulation management.

In a recent study, Duke University researchers Gregory P. Samsa, Ph.D., and David Matchar, M.D., review the evidence that correlates more frequent testing with improved patient outcomes and discuss the implications of these findings for the design of randomized controlled trials that would compare PSM with high quality anticoagulation management outside the home. From the limited studies now available, they infer that more frequent testing could increase the time during which the patient's blood is thinned to the recommended target range (time in target range = TTR). They further conclude that the relationship between TTR and clinical outcomes (that is, bleeding and thromboembolism) is sufficiently strong to support the use of TTR as a primary outcome variable in any randomized controlled trial assessing the effectiveness and cost-effectiveness of PSM. Dr. Matchar is the principal investigator and Dr. Samsa is the project director of the Stroke Prevention Patient Outcomes Research Team (PORT), which is supported by the Agency for Healthcare Research and Quality (PORT contract 290-91-0028).

For more details, see "Relationship between test frequency and outcomes of anticoagulation: A literature review and commentary with implications for the design of randomized trials of patient self-management," by Drs. Samsa and Matchar, in the Journal of Thrombosis and Thrombolysis 9, pp. 283-292, 2000.

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