Neither baseline tests of molecular hypercoagulability nor D-dimer levels predict deep venous thrombosis in critically ill medical-surgical patients

Objective Predicting patients who are harboring asymptomatic deep venous thrombosis (DVT), or who are at particular risk of developing DVT, is a desirable clinical goal since prevention or early treatment of DVT might reduce the risk of fatal pulmonary embolism. Thus validation of simple laboratory tests that reliably predict venous thromboembolism (VTE) would be clinically very important. Tests that might be useful for these applications include markers of hypercoagulability (predicting patients at risk of DVT) and D-dimer (predicting which patients may have acute DVT).Methods In a prospective cohort study we measured a panel of hypercoagulability markers at the time of ICU admission, and six commercial D-dimer assays were performed serially during the ICU stay in medical-surgical ICU patients who were screened for DVT with biweekly lower limb compression ultrasonography. Ultrasonography was also performed at the time of any clinically suspected DVT events. We matched cases with DVT with controls without DVT for length of stay in the ICU to generate receiver operating characteristics (ROC) curves.Results One hundred ninety-seven patients were enrolled. Blood was collected on a total of 763 occasions (median number of occasions per patient: 3, range 1–21). None of the assays predicted DVT, as indicated by the areas under the ROC curves, that did not differ significantly from 50%.Conclusion In critically ill patients, neither tests of hypercoagulability nor D-dimer levels predict patients at risk of DVT and thus they should not be used to guide diagnostic testing for DVT.This study was funded by the Heart and Stroke Foundation of Canada, and the Canadian Institutes of Health Research.