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D-dimer test on the AQT90 FLEX immunoassay analyser

D-dimer is a coagulation marker used as an aid in the diagnosis of venous thromboembolism

Introduction to Venous thromboembolism

Venous thromboembolism (VTE) is a condition in which a blood clot forms in a deep vein.
The clot or a fragment of the clot may break free and enter the circulation as an embolus, which might end up completely obstructing one of the blood vessels in the lungs causing a pulmonary embolism.

A D-dimer test is used as an aid in the diagnosis of detecting if the patient is suffering from deep vein thrombosis (DVT) and/or pulmonary embolism (PE).

DVT is a relatively frequent condition. It involves clot formation in the deep veins of the body, most frequently in the legs. The clots may grow very large and block the blood flow.

The patient presents with symptoms such as: leg pain, tenderness, swelling, change in colour and oedema.
Due to the high risk of complications like pulmonary embolism, which can be fatal, urgent D-dimer testing, diagnosis and treatment are needed.

A D-dimer test is used to spot what is easily missed – and potentially fatal - an aid in the diagnosis of VTE [1,2,3]

D-dimer test on the AQT90 FLEX analyzer

  • 10-30 % PE mortality
  • 650,000 PE deaths every year in the US, the third most common cause of death
  • 400,000 PE diagnoses missed in US patients, approx. 100,000 of these patients die
  • 60 % share of hospital deaths involving PE, diagnosis is  missed in about 70 % of these cases
  • 10 % patients with acute PE who die within the first 60 minutes
  • One out of three patients who survive an initial PE die of a recurrent PE

A quality D-dimer test needs to have:

  1. A high negative predictive value (NPV). This tells you how sure you can be that the patients you rule out do not have VTE.
  2. High specificity which minimizes imaging on healthy patients.

How to use a D-dimer test [4,5]

  • D-dimer single test - Sufficient to safely rule out DVT*
  • D-dimer + NT-proBNP - Effective to distinguish PE diagnosis from heart failure
  • D-dimer + NT-proBNP and/or troponin I/T – Useful for  determining PE prognosis

* When used in combination with clinical probability assessment

The AQT90 FLEX D-dimer test demonstrates [6]:

A high NPV, comparable to the values of the best of its competitors – which means less risk of sending ill patients home without treatment.

A very high specificity (a low number of false positive results) - This means less unnecessary and costly imaging on patients without VTE, and more time to spend on the patients who do, in fact, have VTE.

The AQT90 FLEX D-dimer test offers*

  1. More certainty of ruling out healthy patients
  2. More money to be saved on imaging
  3. More time to spend on the patients who are, in fact, ill

* When used in combination with clinical probability assessment

Basic facts on AQT90 FLEX D-dimer immunoassay test

D-dimer test on the AQT90 FLEX analyzer
  • Specificity  71 %
  • Sensitivity 98 % [7]
  • Reference ranges (95th percentile)
    < 50 years – 630 µg/L
    > 50 years – 654 µg/L
  • Cut-off 500 µg/L

  1. CDC Data & Statistics, Deep Vein Thrombosis (DVT)/Pulmonary Embolism (PE), available at
  2. Calder KK et al: The mortality of untreated pulmonary embolism in emergency department patients. Ann Emerg Med 2005; 45:  302-10
  3. Laack TA, Goyal DG: Pulmonary embolism: an unsuspected killer. Emerg Med Clin N Am 2004; 22: 961–8344.Ref:
  4. Bates SM et al. Chest 2012; 141(2 Suppl): e351S-418S
  5. Konstantinides SV et al. Eur Heart J. 2014 Nov 14;35(43):3033-696.  
  6. AQT90 FLEX D-dimer CE mark study
  7. Sidelmann JJ, Gram J, Larsen A, Overgaard K, Jespersen J.  Thromb Res. 2010;126:524–530

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