title: D-dimer use for deep venous thrombosis exclusion in elderly patients: a comparative analysis of three different approaches to establish cut-off values for an assay with results expressed in D-dimer units.
abstract: BACKGROUND
  The use of adapted cut-off values in the elderly, combined with clinical probability (PTP), increases the proportion of patients in whom venous thromboembolism (VTE) can be safely excluded, compared with the conventional cut-off value of 500 μg/L fibrinogen equivalent units (FEU). We evaluated the clinical performance of three different approaches to establish cut-off values for a D-dimer assay whose results are expressed in D-dimer units (D-DU).
  
  
  METHODS
  HemosIL D-dimer HS assay (Instrumentation Laboratory) was performed in 279 consecutive outpatients with suspected deep venous thrombosis (DVT) and nonhigh PTP.
  
  
  RESULTS
  Considering patients >60 years, the number of negative D-dimer results increased using the modified (376 ng/mL if ≥60 years) and the age-adjusted cut-off (age years × 5 ng/mL if >50 years) compared to the conventional one (230 ng/mL for all patients; 54.6%, 58.2%, and 25.0%, respectively), with no false-negative results. The higher increase was observed in patients >80 years (43.9%, 56.1%, and 8.8%, respectively).
  
  
  CONCLUSIONS
  For the HemosIL D-dimer HS, the use of specific cut-off values in older subjects with suspected DVT and nonhigh PTP increases the number of patients in whom DVT can be safely excluded.
authors.affiliation: Department of Angiology and Blood Coagulation 'Marino Golinelli', University Hospital S. Orsola-Malpighi, Bologna, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Cini
authors.forename: C
authors.initials: C
authors.lastname: Legnani
authors.forename: M
authors.initials: M
authors.lastname: Frascaro
authors.forename: M
authors.initials: M
authors.lastname: Sartori
authors.forename: B
authors.initials: B
authors.lastname: Cosmi
authors.forename: G
authors.initials: G
authors.lastname: Palareti
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001681:Biological Assay / Q000592:standards*; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D005340:Fibrinogen / Q000032:analysis; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D054556:Venous Thromboembolism / Q000097:blood / Q000175:diagnosis*; D020246:Venous Thrombosis / Q000097:blood / Q000175:diagnosis*
chemical_list: D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D; D005340:Fibrinogen
keywords: D-dimer; cut-offs; deep venous thrombosis; elderly; exclusion