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This Article Full Text (PDF) All Versions of this Article: chest.08-0344v1 134/4/789    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to My Personal Article Archive Download to citation manager Google Scholar Articles by Gibson, N. S. Articles by Buller, H. R. PubMed PubMed Citation Articles by Gibson, N. S. Articles by Buller, H. R.

The importance of clinical probability assessment in interpreting a normal D-dimer in patients with suspected pulmonary embolism

¹Department of Vascular Medicine, Academical Medical Center, Amsterdam, the Netherlands ²Department of Internal Medicine, Slotervaart Hospital, Amsterdam, the Netherlands ³Department of General internal Medicine, Leiden University Medical Center, Leiden, the Netherlands

n.s.gibson{at}amc.uva.nl

Abstract

BackgroundThe measurement of the D-dimer concentration test is a widely applied test in the diagnostic work-up of patients with suspected pulmonary embolism. The objective of this study was to investigate how often the D-dimer test fails when clinical probability is not taken into account.

MethodsWe used data collected in 1722 consecutive patients with clinically suspected PE to analyze the three months venous thromboembolism (VTE) rate in all patients with a normal D-dimer concentration and separately for patients with a normal D-dimer with an unlikely or likely clinical probability for pulmonary embolism, as assessed by the Wells clinical decision rule.

ResultsThe 3 month VTE rate in all patients with a normal D-dimer concentration (N=563) was 2.3% (95% CI: 1.4-3.9%). In the patients with an unlikely probability (N=477) VTE was confirmed in 1.1% of the patients with a normal D-dimer (95% CI: 0.4-2.4%). In those with a likely clinical probability (N=86) VTE was confirmed in 9.3% of the patients with a normal D-dimer (95% CI: 4.8-17.3%). The difference of the VTE incidence between the unlikely and the likely probability categories was significant (p<0.001).

ConclusionsOur findings indicate that it is of utmost importance to first examine the patient and assess the clinical probability after which the D-dimer result can be taken into account, in order to prevent that physicians will be influenced by a normal D-dimer test result when they evaluate the clinical probability. Patients with a likely clinical probability should undergo further testing, regardless the D-dimer outcome.