Thromb Haemost 2017; 117(10): 1937-1943
DOI: 10.1160/TH17-03-0182
Stroke, Systemic or Venous Thromboembolism
Schattauer GmbH

Comparison of clinical probability-adjusted D-dimer and age-adjusted D-dimer interpretation to exclude venous thromboembolism

Sarah Takach Lapner
1  Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
2  Department of Medicine, McMaster University, Hamilton, Ontario, Canada
,
Jim A. Julian
3  Ontario Clinical Oncology Group, Hamilton, Ontario, Canada
,
Lori-Ann Linkins
2  Department of Medicine, McMaster University, Hamilton, Ontario, Canada
4  Thrombosis and Atherosclerosis Research Institute, Hamilton, Ontario, Canada
,
Shannon M. Bates
2  Department of Medicine, McMaster University, Hamilton, Ontario, Canada
4  Thrombosis and Atherosclerosis Research Institute, Hamilton, Ontario, Canada
,
Clive Kearon
2  Department of Medicine, McMaster University, Hamilton, Ontario, Canada
4  Thrombosis and Atherosclerosis Research Institute, Hamilton, Ontario, Canada
› Author Affiliations
Financial support: There was no external funding for this study. The STA-Liatest D-Dimer assays used in this study were provided by Diagnostica Stago (Asnières, France) and D-dimer testing was performed by the Hemostasis Reference Laboratory (Hamilton, Ontario, Canada). Dr. Bates receives salary support as the Eli Lily Canada/May Cohen Chair in Women’s Health. Dr. Kearon is supported by an Investigator Award from the Heart & Stroke Foundation of Canada and the Jack Hirsh Professorship in Thromboembolism.
Further Information

Publication History

Received: 14 March 2017

Accepted after major revision: 21 June 2017

Publication Date:
08 November 2017 (online)

Summary

Two new strategies for interpreting D-dimer results have been proposed: i) using a progressively higher D-dimer threshold with increasing age (age-adjusted strategy) and ii) using a D-dimer threshold in patients with low clinical probability that is twice the threshold used in patients with moderate clinical probability (clinical probability-adjusted strategy). Our objective was to compare the diagnostic accuracy of age-adjusted and clinical probability-adjusted D-dimer interpretation in patients with a low or moderate clinical probability of venous thromboembolism (VTE). We performed a retrospective analysis of clinical data and blood samples from two prospective studies. We compared the negative predictive value (NPV) for VTE, and the proportion of patients with a negative D-dimer result, using two D-dimer interpretation strategies: the age-adjusted strategy, which uses a progressively higher D-dimer threshold with increasing age over 50 years (age in years × 10 µg/L FEU); and the clinical probability-adjusted strategy which uses a D-dimer threshold of 1000 µg/L FEU in patients with low clinical probability and 500 µg/L FEU in patients with moderate clinical probability. A total of 1649 outpatients with low or moderate clinical probability for a first suspected deep vein thrombosis or pulmonary embolism were included. The NPV of both the clinical probability-adjusted strategy (99.7%) and the age-adjusted strategy (99.6%) were similar. However, the proportion of patients with a negative result was greater with the clinical probability-adjusted strategy (56.1% vs, 50.9%; difference 5.2%; 95% CI 3.5% to 6.8%). These findings suggest that clinical probability-adjusted D-dimer interpretation is a better way of interpreting D-dimer results compared to age-adjusted interpretation.