Deep vein thrombosis in stroke - The use of plasma D-dimer level as a screening test in the rehabilitation setting

Background and Purpose Venous thromboembolism is a leading cause of morbidity and mortality during the acute recovery period after stroke. This study investigated the utility of plasma D-dimer level as a diagnostic test for deep vein thrombosis (DVT) in patients hospitalized for stroke rehabilitation. Method Plasma samples were drawn from 105 nonambulatory rehabilitation patients with recent ischemic or hemorrhagic stroke and assayed for D-dimer with an enzyme-linked immunosorbent method. Samples were drawn within 24 hours of venous duplex ultrasound (VDU) screening for DVT. Optimal discriminant analysis was used to determine whether plasma D-dimer level, age, sex, days after stroke onset, stroke etiology, National Institutes of Health Stroke Scale score, and ambulatory status could correctly classify patients' DVT status. Results Fourteen of 105 patients had DVT identified by VDU scan. Of all attributes, only D-dimer level had significant ability to discriminate between patients with or without DVT (P<.0001). The optimal cut point for predicting DVT was D-dimer = 1591 ng/mL, resulting in 79% sensitivity, 78% specificity, 35% positive predictive value, and 96% negative predictive value. Reducing the D-dimer cut point to 1092 ng/mL improved both sensitivity and negative predictive value to 100% but reduced specificity to 66% and positive predictive value to 31%. Conclusions A D-dimer level less than or equal to 1092 ng/mL can exclude the presence of DVT in stroke rehabilitation patients. When a D-dimer level >1092 ng/mL occurs, further diagnostic testing is necessary to confirm DVT. Plasma D-dimer level is a simple and inexpensive screening test for DVT during stroke rehabilitation.