title: Clinical conditions and patient factors significantly influence diagnostic utility of D-dimer in venous thromboembolism.
abstract: Determining D-dimer levels remains important in the diagnostic algorithms for venous thromboembolism (VTE). The present study aimed to identify factors influencing D-dimer utility in diagnosing VTE. Consecutive symptomatic medical patients, who attended our emergency department from 1 November 2006 to 31 December 2006, had D-dimer levels measured as fibrinogen equivalent units (FEU), following clinical risk assessment. Diagnosis of VTE was established by venous compression ultrasonography and computed tomographic pulmonary angiography. VTE-negative patients were followed for 2 months to detect future occurrence of thromboembolism. Impact of various factors on D-dimer levels was analyzed. Four thousand and twenty-six patients attended our emergency department, and 525 patients (median age 52 years) had D-dimer assessed. Final diagnosis of VTE was established in 25 (4.7%) patients on radiological investigations. Median D-dimer levels for VTE-negative patients less than 60 years old, with normal renal function and chest radiology were 0.38 microgFEU/ml (range 0.19-2.3), 0.39 microgFEU/ml (range 0.17-3.5) and 0.39 microgFEU/ml (range 0.1-4.3), respectively. Similar figures for those at least 60 years, with renal impairment and abnormal chest radiology, were 0.75 microgFEU/ml (range 0.22-4.3), 0.52 microgFEU/ml (range 0.17-4.4) and 0.92 microgFEU/ml (range 0.26-5.6), respectively. Factors including patient age, renal function and chest radiology had significant influence on D-dimer levels (P < 0.01). A triad of patient age at least 60 years, renal impairment (modification of diet in renal disease stage 2-5) and abnormal chest radiology had a false positive D-dimer in 96% of patients (n = 72). Use of D-dimer in patients with a triad of advanced age, renal impairment and abnormal chest radiology has no practical diagnostic value in VTE.
authors.affiliation: Department of Internal Medicine, Naas General Hospital, Kildare, Trinity College Dublin, Dublin, Ireland. qasima@tcd.ie
authors.forename: Asghar
authors.initials: A
authors.lastname: Qasim
authors.forename: Mary
authors.initials: M
authors.lastname: Duggan
authors.forename: Niamh
authors.initials: N
authors.lastname: O'Connell
authors.forename: Anne
authors.initials: A
authors.lastname: O'Driscoll
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography / Q000379:methods; D004636:Emergency Service, Hospital; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D006801:Humans; D007674:Kidney Diseases / Q000097:blood / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods; D014463:Ultrasonography / Q000379:methods; D054556:Venous Thromboembolism / Q000097:blood* / Q000000981:diagnostic imaging
chemical_list: D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D