Discretionary Thrombophilia Test Acquisition and Outcomes in Patients With Venous Thromboembolism in a Real‐World Clinical Setting

BACKGROUND: The value of thrombophilia test acquisition in improving risk prediction beyond clinical presentation remains unknown. We investigated the effect of thrombophilia test acquisition on venous thromboembolism (VTE) outcomes. METHODS AND RESULTS: We performed a retrospective cohort study of adult patients over a 15‐year period (September 2001 and May 2016) with first diagnosis of VTE in a single academic medical center. Participants were identified by International Classification of Diseases, Ninth Revision (ICD‐9), Current Procedural Terminology (CPT) codes and medication history. Participants with thrombophilia testing were matched to control participants without thrombophilia testing using a propensity model. Primary outcomes included recurrent VTE, anticoagulant use 12 months after the index VTE event, bleeding‐related hospitalization, and death. From 3590 unique patients who met the inclusion criteria, 747 participants with VTE who underwent thrombophilia testing were matched to a control participant without testing. Tested participants were more likely to have a recurrent event (46.1% versus 28.5%; P<0.001) and an anticoagulant prescription 12 months from the index event (53.9% versus 37.1%; P<0.001) but had no significant difference in bleeding‐related hospitalization (11.4% versus 11.8%; P=0.81) compared with untested participants. An abnormal thrombophilia test result, per se, did not predict recurrent VTE (47.8% versus 44.1%; P=0.13), longer duration anticoagulation (53.2% versus 54.8%; P=0.51), bleeding (11.5% versus 11.3%; P=0.70), or mortality (12.2% versus 16.1%; P=0.18) compared with participants who had normal test results. CONCLUSIONS: The decision to perform thrombophilia testing, but not the test result, is associated with a high risk of recurrent VTE despite a greater likelihood of long‐duration anticoagulation.