title: Using an age-dependent D-dimer cut-off value increases the number of older patients in whom deep vein thrombosis can be safely excluded.
abstract: BACKGROUND
  D-dimer testing to rule out deep vein thrombosis is less useful in older patients because of a lower specificity. An age-adjusted D-dimer cut-off value increased the proportion of older patients (>50 years) in whom pulmonary embolism could be excluded. We retrospectively validated the efficacy of this cut-off combined with clinical probability for the exclusion of deep vein thrombosis.
  
  
  METHODS
  Five management study cohorts of 2818 consecutive outpatients with suspected deep vein thrombosis were used. Patients with non-high or unlikely probability of deep vein thrombosis were included in the analysis; four different D-dimer tests were used. The proportion of patients with a normal D-dimer test and the failure rates were calculated using the conventional (500 μg/L) and the age-adjusted D-dimer cut-off (patient's age x 10 μg/L in patients >50 years).
  
  
  RESULTS
  In 1672 patients with non-high probability, deep vein thrombosis could be excluded in 850 (51%) patients with the age-adjusted cut-off value versus 707 (42%) patients with the conventional cut-off value. The failure rates were 7 (0.8; 95% confidence interval 0.3-1.7%) for the age-adjusted cut-off value and 5 (0.7%, 0.2-1.6%) for the conventional cut-off value. The absolute increase in patients in whom deep vein thrombosis could be ruled out using the age-adjusted cut-off value was largest in patients >70 years: 19% among patients with non-high probability.
  
  
  CONCLUSIONS
  The age-adjusted cut-off of the D-dimer combined with clinical probability greatly increases the proportion of older patients in whom deep vein thrombosis can be safely excluded.
authors.affiliation: Department of Vascular Medicine, Academic Medical Center, F4. Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands. r.a.douma@amc.uva.nl
authors.forename: Renée A
authors.initials: RA
authors.lastname: Douma
authors.forename: Melanie
authors.initials: M
authors.lastname: Tan
authors.forename: Roger E G
authors.initials: RE
authors.lastname: Schutgens
authors.forename: Shannon M
authors.initials: SM
authors.lastname: Bates
authors.forename: Arnaud
authors.initials: A
authors.lastname: Perrier
authors.forename: Cristina
authors.initials: C
authors.lastname: Legnani
authors.forename: Douwe H
authors.initials: DH
authors.lastname: Biesma
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Ginsberg
authors.forename: Henri
authors.initials: H
authors.lastname: Bounameaux
authors.forename: Gualtiero
authors.initials: G
authors.lastname: Palareti
authors.forename: Marc
authors.initials: M
authors.lastname: Carrier
authors.forename: Gerben C
authors.initials: GC
authors.lastname: Mol
authors.forename: Grégoire
authors.initials: G
authors.lastname: Le Gal
authors.forename: Pieter W
authors.initials: PW
authors.lastname: Kamphuisen
authors.forename: Marc
authors.initials: M
authors.lastname: Righini
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012016:Reference Values; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D020246:Venous Thrombosis / Q000097:blood / Q000175:diagnosis*
chemical_list: D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D