Elevated levels of D-dimer and fragment 1+2 upon central venous catheter insertion and factor V Leiden predict subclavian vein thrombosis.

Symptomatic subclavian vein thrombosis is a potential complication in approximately 5-10% patients with indwelling central venous catheters. Having reliable tests that would identify those patients with a high risk of catheter-related thrombosis would be clinically useful by helping to tailor thromboprophylaxis. In this case control study by Jansen et al. (see page 499), patients with a Hickman catheter who were undergoing allogeneic bone marrow transplantation for hematological malignancies were investigated. Baseline levels of D-dimer and fragment 1+2 were found to be significantly higher in patients who developed catheter-related thrombosis and the presence of factor V Leiden genotype was found only in patients with thrombosis. Although these abnormalities were associated with a 5- to 7-fold increased risk of catheter-related thrombosis, the positive predictive values for elevated D-dimer and fragment 1+2 levels were only 80% while the negative predictive values were about 40%. These results support the concept that laboratory evidence of activation of coagulation correlates with clinical thrombotic events, but they are insufficient for recommending routine testing of these markers in patients with central venous catheters. Further studies are required to confirm these findings and to see if similar results are observed in patients with other malignancies.