title: Excluding pulmonary embolism in primary care using the Wells-rule in combination with a point-of care D-dimer test: a scenario analysis.
abstract: BACKGROUND
  In secondary care the Wells clinical decision rule (CDR) combined with a quantitative D-dimer test can exclude pulmonary embolism (PE) safely. The introduction of point-of-care (POC) D-dimer tests facilitates a similar diagnostic strategy in primary care.We estimated failure-rate and efficiency of a diagnostic strategy using the Wells-CDR combined with a POC-D-dimer test for excluding PE in primary care.We considered ruling out PE safe if the failure rate was <2% with a maximum upper confidence limit of 2.7%.
  
  
  METHODS
  We performed a scenario-analysis on data of 2701 outpatients suspected of PE. We used test characteristics of two qualitative POC-D-dimer tests, as derived from a meta-analysis and combined these with the Wells-CDR-score.
  
  
  RESULTS
  In scenario 1 (SimpliRed-D-dimer sensitivity 85%, specificity 74%) PE was excluded safely in 23.8% of patients but only by lowering the cut-off value of the Wells rule to <2. (failure rate: 1.4%, 95% CI 0.6-2.6%)In scenario 2 (Simplify-D-dimer sensitivity 87%, specificity 62%) PE was excluded safely in 12.4% of patients provided that the Wells-cut-off value was set at 0. (failure rate: 0.9%, 95% CI 0.2-2.6%)
  
  
  CONCLUSIONS
  Theoretically a diagnostic strategy using the Wells-CDR combined with a qualitative POC-D-dimer test can be used safely to exclude PE in primary care albeit with only moderate efficiency.
authors.affiliation: Department of General Practice, Academic Medical Centre, Amsterdam, The Netherlands. w.a.lucassen@amc.uva.nl
authors.forename: Wim A M
authors.initials: WA
authors.lastname: Lucassen
authors.forename: Renée A
authors.initials: RA
authors.lastname: Douma
authors.forename: Diane B
authors.initials: DB
authors.lastname: Toll
authors.forename: Harry R
authors.initials: HR
authors.lastname: Büller
authors.forename: Henk C P M
authors.initials: HC
authors.lastname: van Weert
mesh_terms: D000553:Ambulatory Care; D000933:Antifibrinolytic Agents / Q000097:blood; D020000:Decision Support Systems, Clinical / Q000706:statistics & numerical data*; D003937:Diagnosis, Differential; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis; D006801:Humans; D015201:Meta-Analysis as Topic; D019095:Point-of-Care Systems / Q000706:statistics & numerical data*; D011237:Predictive Value of Tests; D011320:Primary Health Care / Q000379:methods*; D011655:Pulmonary Embolism / Q000097:blood / Q000175:diagnosis*; D036301:Qualitative Research; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity
chemical_list: D000933:Antifibrinolytic Agents; D005338:Fibrin Fibrinogen Degradation Products; D011933:Reagent Kits, Diagnostic; C036309:fibrin fragment D