ISTH Congress Abstracts

Official abstracts site for the ISTH Congress

MENU 

A Simplified Decision Rule to Rule out Deep Vein Thrombosis Using Clinical Assessment and D-dimer

1Department of Statistics and Actuarial Science, University of Waterloo, Kitchener, Canada, 2Department of Medicine, McMaster University, Hamilton, Canada, 3Thrombosis and Atherosclerosis Research Institute, McMaster University, Hamilton, Canada, 4Julius Centre for Health Sciences and Primary Care, University Medical Centre Utrecht, Utrecht, Netherlands, 5Department of Emergency Medicine, Lund University, Lund University Hospital, Lund, Sweden, 6Department of Oncology, McMaster University, Hamilton, Canada, 7Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Canada

Abstract Number: PB1182

Meeting: ISTH 2021 Congress

Theme: Venous Thromboembolism » VTE Diagnosis

Background: Current clinical decision rules to exclude deep vein thrombosis (DVT) are under-utilized partly because of their complexity.

Aims: To develop a new simple clinical decision rule to safely exclude DVT using D-dimer and Wells-rule items.

Methods: We used individual patient data from four prospective outpatient diagnostic DVT studies. A bootstrap approach with logistic regression was used to select Wells-rule items that would form the new clinical decision rule. Risk groups were then defined based on combinations of the selected items. D-dimer was applied with predetermined thresholds of < 500 ng/mL; 500 to 999 ng/mL; and ≥1,000 ng/mL to rule out DVT. DVT was considered safely excluded if the upper 95% confidence interval (CI) of DVT prevalence was < 2%.

Results: Four studies and 3368 patients were included in the analysis. Overall prevalence of DVT was 17%. In addition to D-dimer, ‘calf swelling > 3 cm’ and ‘DVT as the most likely diagnosis’ were included in the new rule. Based on these two variables, two clinical pre-test probability (CPTP) groups were defined; low (none of the two items present) and high (at least one of the items present). DVT can be safely excluded in patients with low CPTP with a D-dimer < 500 ng/mL (prevalence = 0.1%; 95% CI: 0.0-0.8%), low CPTP with a D-dimer between 500 ng/mL and 999 ng/mL (prevalence = 0.3%; 95% CI: 0.0-1.7%), and high CPTP with D-dimer < 500 ng/mL (prevalence = 0.3%; 95% CI: 0.0-1.0%).

Conclusions: We derived a simple clinical decision rule with 3 items as shown in Figure 1. The results suggest that the rule can safely exclude DVT. Prospective validation is required.

Diagnostic work-up for suspected deep vein thrombosis (DVT) using the new rule.

To cite this abstract in AMA style:

Xu K, de Wit K, Geersing G-, Takada T, Schutgens R, Elf J, Kearon C, SP. A Simplified Decision Rule to Rule out Deep Vein Thrombosis Using Clinical Assessment and D-dimer [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/a-simplified-decision-rule-to-rule-out-deep-vein-thrombosis-using-clinical-assessment-and-d-dimer/. Accessed May 16, 2022.

« Back to ISTH 2021 Congress

ISTH Congress Abstracts - https://abstracts.isth.org/abstract/a-simplified-decision-rule-to-rule-out-deep-vein-thrombosis-using-clinical-assessment-and-d-dimer/