A simplified decision rule to rule out deep vein thrombosis using clinical assessment and D-dimer

J Thromb Haemost. 2021 Jul;19(7):1752-1758. doi: 10.1111/jth.15337. Epub 2021 May 4.

Abstract

Background: Current clinical decision rules to exclude deep vein thrombosis (DVT) are underused partly because of their complexity. A simplified rule that can be easily applied would be more appealing to use in clinical practice.

Methods: We used individual patient data from prospective diagnostic studies of patients suspected of DVT to develop a new clinical decision rule. The primary outcome was presence of DVT either at initial testing or during follow-up. DVT was considered safely excluded if the upper 95% confidence interval (CI) of DVT prevalence was <2%.

Results: Four studies and 3368 patients were eligible for this analysis. Overall prevalence of DVT was 17%. In addition to D-dimer, two variables, calf swelling and DVT as the most likely diagnosis, are included in the new rule. Based on these two variables, two clinical pretest 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 1000 ng/ml (prevalence = 0.3%; 95% CI, 0.0-1.7), and D-dimer <500 ng/ml in patients with high CPTP (prevalence = 0.3%; 95% CI, 0.0-1.0).

Conclusions: The combination of D-dimer and Wells items resulted in a simple clinical decision rule with 3 items. The results suggest that the rule can safely exclude DVT. Prospective validation is required.

Keywords: deep vein thrombosis; diagnosis; fibrinogen; ultrasonography; venous thromboembolism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Fibrin Fibrinogen Degradation Products
  • Humans
  • Predictive Value of Tests
  • Prospective Studies
  • Ultrasonography
  • Venous Thrombosis* / diagnosis

Substances

  • Fibrin Fibrinogen Degradation Products
  • fibrin fragment D