Use of Factor V Leiden genetic testing in practice and impact on management

To assess the use of the genetic test for Factor V Leiden in clinical practice, physician adherence to national and local guidelines, and impacts of test results on patient management.

Chart review of all patients tested for Factor V Leiden during a 1-year period (2003) in a large nonprofit health care system (group health) (n = 272).

The test for Factor V Leiden was most often used in nonacute outpatient settings by primary care practitioners, in combination with other tests for procoagulant disorders. Testing was performed more broadly than recommended: 61% of tests met American College of Medical Genetics guidelines, 46% of tests met CAP guidelines, and 37% of tests met group health internal guidelines. The most common rationale for testing was to explain a clinical event (58%). Patient management was modified more often in heterozygotes (54%) than in those with normal results (13%) (P < 0.0001).

The uptake of the test for Factor V Leiden has not followed existing recommendations. Genetic risk information was used to influence patient management in the absence of supporting evidence related to health outcomes. These results underscore the importance of further research concerning effective prevention and treatment strategies for patients with genetic risk to help translate genetic risk information into improved health outcomes.