Haematologica 2001; 86:E28

[prev] [index] [next]

Diagnosis Of Deep Venous Thrombosis In The Elderly: A Higher D-Dimer Cut-Off Value Is Better?

Carlos Aguilar,* Angel Martinez,° Angela Martinez,° Concepción Del Rio,° Mar Vazquez^
*Department Of Haematology And ^Preventive Medicine. Hospital General Del Insalud. Soria; °Resident In Family Medicine. Hospital General Del Insalud. Soria. Spain

Correspondence: Dr. Carlos Aguilar, Department of Haematology, Hospital General del INSALUD, Paseo de Santa Bárbara s/n, 42.002 Soria (Spain). Telephone: +34-975-214156. Fax: +34-975-234305e-mail address: caraguilar@excite.com
medline ref.
Abstract

D-dimer has proved to be a useful tool for the diagnostic approach of venous thromboembolism. Baseline d-dimer levels tend to increase with age so we have tried to find out whether a higher d-dimer cut-off value would translate into any improvement in the diagnostic accuracy of this parameter in elderly outpatients with suspected deep venous thrombosis.

Text

D-dimer (DD) has been extensively investigated during the recent years and has been consistently found to be of value in the diagnostic approach of venous thromboembolism (VTE);1 when assayed by ELISA or some of the recently developed rapid and quantitative (based on monoclonal antibody-coated latex particle agglutination) methods DD has been found to have a high sensitivity and negative predictive value (NPV) which allows to reasonably rule out deep venous thrombosis (DVT) and especially pulmonary embolism (PE). These two types of DD assays have shown similar degrees of diagnostic accuracy in the setting of VTE2 with the latter being more convenient for routine use in an emergency laboratory though. A lower usefulness of DD in elderly patients with suspected VTE due mainly to a lower specificity of this test in this subset of patients has been reported.3,4 Since baseline DD levels tend to increase with age4,5 we hypothesised that increasing the DD cut-off value (to 0.6 mg/mL) might translate into a higher diagnostic yield of the test in elderly outpatients with suspected DVT when compared to the cut-off value of 0.4 mg/mL recommended by the manufacturer.
A series of 200 consecutive patients of 70 years of age or older, presenting in the Emergency Department of our hospital with a clinical suspicion of DVT underwent simultaneously lower limb compression ultrasonography (and additional venography when considered clinically indicated) and DD assay (STA Liatest® D-Di, Diagnostica Stago, Asnières, France). DVT was confirmed in 40 patients (20%) with both cut-off values. Sensitivity, specificity and predictive values of DD for the diagnosis of DVT with both cut-off levels are summarized in Table 1. Our results show that increasing the DD cut-off value as a part of the diagnostic strategy of DVT in the elderly leads to a slight decrease in sensitivity (2.5%) and an increase in specificity (22.3%) which however does not translate into a higher NPV; these findings could be regarded as devoid of clinical relevance since the exclusion of VTE is currently the main indication of DD measurement. Other reports using the same DD assay and cut-off value have given similar NPV results for patients of similar age.2,6 Therefore the standard cut-off value (0.4 mg/mL) is associated to a similar NPV but less false negative results than a higher level and consequently the convenience for that change is not warranted. This issue has been controversial in previous studies in which different policies have been suggested.3,7
Following our findings DD can rule out DVT in a non-invasive way in the elderly with a high degree of accuracy even though some authors have pointed out that a NPV below 98% (just marginally over our value) should be considered suboptimal to safely exclude DVT2; interestingly enough in contrast to previous conclusions the sensitivity, specificity and NPV recorded in our group of patients are fairly similar to those found by ourselves for younger outpatients using a cut-off of 0.4 mg/mL (data not published).
As a consequence an initial DD test in elderly outpatients with suspected DVT can result in a cost reduction and combined with clinical probability and radiologic resources can be considered safe.2,8 The use of confirmation methods could be limited to patients with a positive DD but could also be justified in a minority of selected patients with a negative result and still a very high clinical probability of DVT.

References

  1. Perrier A, Desmarais S, Miron MJ, de Moerloose P, Lepage R, Slosman D et al. Non-invasive diagnosis of venous thromboembolism in outpatients. Lancet 1999; 353: 190-195.
  2. van der Graaf F, van den Borne H, van der Kolk M, de Wild PJ, Janssen GWT, van Uum SHM. Exclusion of deep venous thrombosis with D-dimer testing. Comparison of 13 D-dimer methods in 99 outpatients suspected of deep venous thrombosis using venography as reference standard. Thromb Haemostas 2000; 83: 191-198.
  3. Le Blanche AF, Siguret V, Settegrana C, Bohus S, Le Masne de Chermont E, Andreux JP et al. Ruling out acute deep vein thrombosis by ELISA plasma D-dimer assay versus ultrasound in inpatients more than 70 years old. Angiology 1999; 50: 873-892.
  4. Tardy B, Tardy-Poncet B, Viallon A, Lafond P, Page Y, Venet C et al. Evaluation of D-dimer ELISA test in elderly patients with suspected pulmonary embolism. Thromb Haemostas 1998; 79: 38-41.
  5. MacCallum PK, Cooper JA, Martin J, Howarth DJ, Meade TW, Miller GJ. Haemostatic and lipid determinants of prothrombin fragments and D-dimer in plasma. Thromb Haemostas 2000; 83: 421-426.
  6. Escoffre-Barbe M, Oger E, Leroyer C, Grimaux M, Le Moigne E, Nonent M et al. Evaluation of a new rapid D-dimer assay for clinically suspected deep venous thrombosis (Liatest D-dimer). Am J Clin Pathol 1998; 109: 748-753.