Limited Usefulness of Tests of Coagulation Defects for Predicting Symptomatic Pulmonary Embolism after an Initial Episode of Deep Vein Thrombosis

Abstract

Objective: To establish the usefulness of currently available tests of coagulation defects for predicting symptomatic pulmonary embolism (PE) in patients with lower extremity deep vein thrombosis (DVT). Methods: Between 1980 and 1996, 294 patients with DVT were followed for a mean period of 7.9 years. The coagulation defects included low activity of antithrom-bin III, protein C, protein S or plasminogen, and positivity for lupus anticoagulant or anticardiolipin antibody. The influences of these coagulation abnorm-alities on PE incidence were analysed, using a Cox regression hazards model. Results: Coagulation defects were found to be an important variable predicting PE (risk ratio = 7.272). ‘PE-free survival’ in patients with no coagulation defect was significantly longer than that in patients with one or more of these defects ( p = 0.0001). The sensitivity of coagulation tests for predicting PE was only 47% despite the negative predictive value of 93%. Conclusions: Determining these defects has limited usefulness in identifying patients who would be appropriate candidates for intensive anticoagulation therapy.