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 ≤ 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.