title: The use of D-dimer testing and Wells score in patients with high probability for acute pulmonary embolism.
abstract: OBJECTIVE
  To investigate if a combination of Wells pre-test probability score and D-dimer testing could be used as a safe base for making clinical decisions on further investigations for patients with intermediate to high risks of pulmonary embolism (PE).
  
  
  METHODS
  One hundred and twenty patients with signs or symptoms of acute PE were investigated with pulmonary angiography (PA) or contrast enhanced computed tomography of the pulmonary arteries (CTPA), D-dimer testing (Tinaquant) and clinical scoring using the Wells pre-test probability score during their first 48 hours at the hospital. Patients were recruited consecutively from emergency departments at two teaching hospitals.
  
  
  RESULTS
  The cut-off value of 0.5 mg L(-1) in D-dimer analysis is proved adequate with a negative predictive value (NPV) of 92% in this group of patients with intermediate to high risks. The combination of D-dimer testing and Wells score increases the NPV to 94%. The specificities of both tests were low.
  
  
  CONCLUSIONS
  D-dimer and Wells pre-test probability scores are safe to rule out acute PE even in patients with at least an intermediate risk of PE, but the specificity is low. D-dimer testing had a higher NPV than Wells score and the combination improved the algorithm further. The cut-off level for a high risk of PE measured with the Wells score was four and it seems reasonable to use that cut-off level in future algorithms. In addition, both PA and CTPA can present false positive and negative results difficult to interpret.
authors.affiliation: Department of Internal Medicine, Karolinska Institutet, Södersjukhuset, Stockholm, Sweden. marten.soderberg@sodersjukhuset.se
authors.forename: Mårten
authors.initials: M
authors.lastname: Söderberg
authors.forename: Johan
authors.initials: J
authors.lastname: Brohult
authors.forename: Lennart
authors.initials: L
authors.lastname: Jorfeldt
authors.forename: Gerd
authors.initials: G
authors.lastname: Lärfars