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

*Corresponding author for this work

Research output: Contribution to journalArticle

56 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 2012

Keywords

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

ASJC Scopus subject areas

  • Hematology

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