title: Qualitative point-of-care D-dimer testing compared with quantitative D-dimer testing in excluding pulmonary embolism in primary care.
abstract: BACKGROUND
  General practitioners can safely exclude pulmonary embolism (PE) by using the Wells PE rule combined with D-dimer testing.
  
  
  OBJECTIVE
  To compare the accuracy of a strategy using the Wells rule combined with either a qualitative point-of-care (POC) D-dimer test performed in primary care or a quantitative laboratory-based D-dimer test.
  
  
  METHODS
  We used data from a prospective cohort study including 598 adults suspected of PE in primary care in the Netherlands. General practitioners scored the Wells rule and carried out a qualitative POC test. All patients were referred to hospital for reference testing. We obtained quantitative D-dimer test results as performed in hospital laboratories. The primary outcome was the prevalence of venous thromboembolism in low-risk patients.
  
  
  RESULTS
  Prevalence of PE was 12.2%. POC D-dimer test results were available in 582 patients (97%). Quantitative test results were available in 401 patients (67%). We imputed results in 197 patients. The quantitative test and POC test missed one (0.4%) and four patients (1.5%), respectively, with a negative strategy (Wells ≤ 4 points and D-dimer test negative) (P = 0.20). The POC test could exclude 23 more patients (4%) (P = 0.05). The sensitivity and specificity of the Wells rule combined with a POC test were 94.5% and 51.0% and, combined with a quantitative test, 98.6% and 47.2%, respectively.
  
  
  CONCLUSIONS
  Combined with the Wells PE rule, both tests are safe to use in excluding PE. The quantitative test seemed to be safer than the POC test, albeit not statistically significant. The specificity of the POC test was higher, resulting in more patients in whom PE could be excluded.
authors.affiliation: Department of Family Medicine, Academic Medical Center, Amsterdam, the Netherlands.
authors.forename: W A M
authors.initials: WA
authors.lastname: Lucassen
authors.affiliation: Department of Family Medicine, University of Maastricht, Maastricht, the Netherlands.
authors.forename: P M G
authors.initials: PM
authors.lastname: Erkens
authors.affiliation: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, the Netherlands.
authors.forename: G J
authors.initials: GJ
authors.lastname: Geersing
authors.affiliation: Department of Vascular Medicine, Academic Medical Center, Amsterdam, the Netherlands.
authors.forename: H R
authors.initials: HR
authors.lastname: Büller
authors.affiliation: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, the Netherlands.
authors.forename: K G M
authors.initials: KG
authors.lastname: Moons
authors.affiliation: Department of Family Medicine, University of Maastricht, Maastricht, the Netherlands.
authors.forename: H E J H
authors.initials: HE
authors.lastname: Stoffers
authors.affiliation: Department of Family Medicine, Academic Medical Center, Amsterdam, the Netherlands.
authors.forename: H C P M
authors.initials: HC
authors.lastname: van Weert
mesh_terms: D015415:Biomarkers / Q000097:blood; D003661:Decision Support Techniques; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D058005:General Practitioners; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D019095:Point-of-Care Systems; D011237:Predictive Value of Tests; D015995:Prevalence; D011320:Primary Health Care / Q000379:methods*; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000097:blood* / Q000175:diagnosis* / Q000453:epidemiology; D015203:Reproducibility of Results; D012307:Risk Factors; D054556:Venous Thromboembolism / Q000097:blood* / Q000175:diagnosis* / Q000453:epidemiology
chemical_list: D015415:Biomarkers; D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D
keywords: D-dimer; bedside testing; clinical prediction rule; primary healthcare; pulmonary embolism