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Could a D-dimer/fibrinogen ratio have a role in ruling-out venous thromboembolism?
  1. Teodoro Marcianò1,
  2. Stefano Franchini2
  1. 1Emergency Department, Ospedale Guglielmo da Saliceto, Piacenza, Italy
  2. 2Emergency Department, San Raffaele Hospital, Milano, Italy
  1. Correspondence to Dr Teodoro Marcianò, Emergency Department, Ospedale Guglielmo da Saliceto, Piacenza 29121, Italy; teodoro.marciano{at}gmail.com

Abstract

Background Diagnosis of venous thromboembolism (VTE) requires chest CT angiography for pulmonary embolism and venous ultrasound for deep vein thrombosis. To reduce imaging, guidelines recommend D-dimer levels to rule-out VTE in patients with a low pre-test probability. The most widely used D-dimer cut-off is 500 ng/mL. This cut-off has low specificity, meaning many patients without disease require imaging.

Methods In this retrospective chart review, we evaluated the diagnostic performance of the D-dimer/fibrinogen ratio (DFR) for identifying thromboembolism and compared it to the performance of two different D-dimer cut-offs (500 ng/mL and 1000 ng/mL) in patients who underwent a chest CT angiography or a venous ultrasound in the ED of San Raffaele Hospital, Italy, in 2017. Patients had a retrospective Wells score calculated after chart review, identifying both high-risk and low-risk pre-test probability patients for this study and low probability patients were further stratified into low-risk of deep vein thrombosis or pulmonary embolism.

Results Enrolled patients included 92 with suspected pulmonary embolism and 154 with suspected deep vein thrombosis; of whom 67 (27%) were diagnosed with VTE. The most accurate cut-off for DFR in terms of discriminative power was 2.65. In the whole sample and in low-risk patients, this cut-off had the same sensitivity values of the 500 ng/mL D-dimer cut-off (97% (95% CI: 89.8% to 99.2%)), while slightly lower sensitivity values were found for the 1000 ng/mL D-dimer cut-off (95.5% (95% CI: 87.6% to 98.5%)). Specificity was higher for the 2.65 DFR cut-off (55.3% (95% CI: 48.0% to 62.4%)) in the whole sample compared with both 500 ng/mL D-dimer cut-off (22.9% (95% CI: 17.4% to 29.6%)) and 1000 ng/mL D-dimer cut-off (45.8% (95% CI: 38.7% to 53.1%)). Similar results were found in all subgroups.

Conclusion A DFR, with a cut-off of 2.65, may improve the specificity for VTE patients when compared with D-dimer alone in high-risk VTE emergency medicine populations. This is exploratory information only, needing evaluation in prospective, multicentre studies, prior to consideration for use in routine clinical work.

  • thrombo-embolic disease
  • diagnosis
  • pulmonary embolism
  • emergency department

Data availability statement

Data are available upon reasonable request.

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Data availability statement

Data are available upon reasonable request.

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Footnotes

  • Handling editor Katie Walker

  • Contributors TM designed the study, collected the data, performed part of the statistical analysis, wrote and revised the manuscript. SF performed part of the statistical analysis, wrote and revised the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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