D-dimer threshold increase with pretest probability unlikely for pulmonary embolism to decrease unnecessary computerized tomographic pulmonary angiography

J. A. Kline, M. M. Hogg, D. M. Courtney, C. D. Miller, A. E. Jones, H. A. Smithline

Research output: Contribution to journalArticle

55 Scopus citations

Abstract

Background: Increasing the threshold to define a positive D-dimer could reduce unnecessary computed tomographic pulmonary angiography (CTPA) for a suspected pulmonary embolism (PE) but might increase rates of a missed PE and missed pneumonia, the most common non-thromboembolic diagnosis seen on CTPA. Objective: Measure the effect of doubling the standard D-dimer threshold for 'PE unlikely' Revised Geneva (RGS) or Wells' scores on the exclusion rate, frequency and size of a missed PE and missed pneumonia. Methods: Patients evaluated for a suspected PE with 64-channel CTPA were prospectively enrolled from emergency departments (EDs) and inpatient units of four hospitals. Pretest probability data were collected in real time and the D-dimer was measured in a central laboratory. Criterion standard was CPTA interpretation by two independent radiologists combined with clinical outcome at 30days. Results: Of 678 patients enrolled, 126 (19%) were PE+ and 93 (14%) had pneumonia. Use of either Wells'≤4 or RGS≤6 produced similar results. For example, with RGS≤6 and standard threshold (<500ngmL -1), D-dimer was negative in 110/678 (16%), and 4/110 were PE+ (posterior probability 3.8%) and 9/110 (8.2%) had pneumonia. With RGS≤6 and a threshold <1000ngmL -1, D-dimer was negative in 208/678 (31%) and 11/208 (5.3%) were PE+, but 10/11 missed PEs were subsegmental and none had concomitant DVT. Pneumonia was found in 12/208 (5.4%) with RGS≤6 and D-dimer<1000ngmL -1. Conclusions: Doubling the threshold for a positive D-dimer with a PE unlikely pretest probability could reduce CTPA scanning with a slightly increased risk of missed isolated subsegmental PE, and no increase in rate of missed pneumonia.

Original languageEnglish (US)
Pages (from-to)572-581
Number of pages10
JournalJournal of Thrombosis and Haemostasis
Volume10
Issue number4
DOIs
StatePublished - Apr 1 2012
Externally publishedYes

Keywords

  • Fibrin fragment D
  • Medical decision making
  • Spiral computed
  • Tomography
  • Venous thromboembolism

ASJC Scopus subject areas

  • Hematology

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