RT Journal Article
SR Electronic
T1 Is utility of D-Dimer test undermined because of overuse in routine clinical practise?
JF European Respiratory Journal
JO Eur Respir J
FD European Respiratory Society
SP p3611
VO 38
IS Suppl 55
A1 Gautam Marwah
A1 Helen Taylor
A1 Selva Selvaraj
A1 Stephen Murphy
YR 2011
UL http://erj.ersjournals.com/content/38/Suppl_55/p3611.abstract
AB Introduction: In suspected VTE a low pre-test probability and negative D-Dimer is associated with risk of VTE &lt; 2%. However d-dimer is raised in many conditions and utility depends on VTE prevalence in population tested (9.5-19% in validation studies). Purpose of study was to assess utility of d-dimer testing in routine practise.Methods: Case records of patients d-dimer tested in A&amp;E or on admission to hospital were reviewed. Data included: clinical features, admission diagnosis and pre-test probability if recorded. Investigators estimated VTE-risk, calculated post-test probability of VTE and impact on imagingResults: 96 cases included; 52% female, mean (SD) age 61yrs. Symptoms: chest pain 44.5%; leg pain/swelling 28%; dyspnea 17%, syncope 7.5%, other 3%. Admission diagnosis: VTE likely 10%, VTE possible 57%, other diagnosis 33%. Pre-test probability done in 23%. Investigator pre-test VTE-risk: High (H) 9%, Moderate (M) 20%, Low (L) 33%, Very Low (V) 38%. D-dimer positive 43% (H 100%, M 64%, L 44%, V 41%; p&lt;0.05). p=0.001. VTE-Imaging if d-dimer +ve (VTE-risk M, L, V): 41% v 11.5% OR 5.1 (1.8-15) p=0.001. Prevalence of VTE was 2.3% (sensitivity 1.0, specificity 0.58; negative likelihood ratio 0.0-1.1). Pre and post-test probability of VTE if negative d-dimer: VTE-risk M-H pre-8%, post-&lt;1%; VTE-risk V-L pre-&lt;2%, post-&lt;1%.Conclusion: Prevalence of VTE in patients D-dimer tested in clinical practise is much lower than in validation studies. Both high risk and very low risk patients with alternative diagnoses are often tested. If VTE risk is very low a negative d-dimer test makes little difference to post-test probability of VTE but positive tests lead to unnecessary imaging.