Research

Potential of an age adjusted D-dimer cut-off value to improve the exclusion of pulmonary embolism in older patients: a retrospective analysis of three large cohorts

BMJ 2010; 340 doi: 10.1136/bmj.c1475 (Published 30 March 2010)
Cite this as: BMJ 2010;340:c1475
  1. Renée A Douma, physician1,
  2. Grégoire le Gal, physician2,
  3. Maaike Söhne, physician1,
  4. Marc Righini, physician3,
  5. Pieter W Kamphuisen, physician1,
  6. Arnaud Perrier, professor4,
  7. Marieke J H A Kruip, physician5,
  8. Henri Bounameaux, professor3,
  9. Harry R Büller, professor1,
  10. Pierre-Marie Roy, professor6
  1. 1Department of Vascular Medicine, Academic Medical Centre, Meibergdreef 9, 1105 AZ, Amsterdam, Netherlands
  2. 2Department of Internal Medicine and Chest Diseases, CHU la Cavale Blanche, Equipe d’accueil 3878 (GETBO), Brest University Hospital, 29609 Brest, France
  3. 3Division of Angiology and Haemostasis, Department of Internal Medicine, Geneva Faculty of Medicine, University of Geneva, CH-1211 Geneva, Switzerland
  4. 4Division of Internal General Medicine, Geneva Faculty of Medicine, University of Geneva, CH-1211 Geneva, Switzerland
  5. 5Department of Haematology, Erasmus Medical Centre, ‘s-Gravendijkwal 230, 3015 CE Rotterdam, Netherlands
  6. 6Department of Emergency Medicine, University of Angers, F-49933 Angers Cedex 9, France
  1. Correspondence to: R A Douma R.A.Douma{at}amc.uva.nl
  • Accepted 6 January 2010

Abstract

Objectives In older patients, the the D-dimer test for pulmonary embolism has reduced specificity and is therefore less useful. In this study a new, age dependent cut-off value for the test was devised and its usefulness with older patients assessed.

Design Retrospective multicentre cohort study.

Setting General and teaching hospitals in Belgium, France, the Netherlands, and Switzerland.

Patients 5132 consecutive patients with clinically suspected pulmonary embolism.

Intervention Development of a new D-dimer cut-off point in patients aged >50 years in a derivation set (data from two multicentre cohort studies), based on receiver operating characteristics (ROC) curves. This cut-off value was then validated with two independent validation datasets.

Main outcome measures The proportion of patients in the validation cohorts with a negative D-dimer test, the proportion in whom pulmonary embolism could be excluded, and the false negative rates.

Results The new D-dimer cut-off value was defined as (patient’s age×10) μg/l in patients aged >50. In 1331 patients in the derivation set with an “unlikely” score from clinical probability assessment, pulmonary embolism could be excluded in 42% with the new cut-off value versus 36% with the old cut-off value (<500 μg/l). In the two validation sets, the increase in the proportion of patients with a D-dimer below the new cut-off value compared with the old value was 5% and 6%. This absolute increase was largest among patients aged >70 years, ranging from 13% to 16% in the three datasets. The failure rates (all ages) were 0.2% (95% CI 0% to 1.0%) in the derivation set and 0.6% (0.3% to 1.3%) and 0.3% (0.1% to 1.1%) in the two validation sets.

Conclusions The age adjusted D-dimer cut-off point, combined with clinical probability, greatly increased the proportion of older patients in whom pulmonary embolism could be safely excluded.

Footnotes

  • Contributors: RAD, GlG, PWK, and PMR conceived and designed the study and performed analysis and interpretation of data. MS, MR, AP, and MJHAK collected and interpreted data. RAD drafted the manuscript. All authors were involved in revision and final approval of the manuscript. All authors had full access to the data in the study.

  • Funding: None

  • Competing interests: All authors have completed the unified competing interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare (1) no financial support for the submitted work from anyone other than their employer; (2) no financial relationships with commercial entities that might have an interest in the submitted work; (3) no spouses, partners, or children with relationships with commercial entities that might have an interest in the submitted work; and (4) no non-financial interests that may be relevant to the submitted work.

  • Ethical approval: Not required.

  • Data sharing: No additional data available.

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited, the use is non commercial and is otherwise in compliance with the license. See: http://creativecommons.org/licenses/by-nc/2.0/ and http://creativecommons.org/licenses/by-nc/2.0/legalcode.

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